3.2 Q4 JTS ASR/Hill Start/Fuel gauge Failure.

[Ascari32]

Has anyone any clues as to why the ASR/VDC/Hill Start and Petrol Gauge should fail in unison on my 3.2 Q4 JTS. I am inclined to think it is related to some bad connection or moisture - it has been getting colder and damp of late. It would be nice to think it is something obvious, but history tells a different story. I do hope it's not some terminal software failure. Aside from these failure indications, the car is running nicely.

And advice would be most welcome.

Cheers,

[bazzbazz]

The USUAL cause is you have lost the connection to your MAF.

Either the MAF has died completely (rare) or the connection to it is bad.

Try disconnecting and cleaning the plug and reconnecting. If the fuel gauge suddenly works you have found the culprit.

[Ascari32]

OK, here's the story. My New camshafts have such a massive valve overlap that the air through the MAF is such that it creates an error which the ECU is unaware of. New MAF flow based on cylinder fill + Crossflow.

So, after much testing I buy a new MAF sensor Bosch 0-280-218-008; fits Volvo XC70. But, it still needed a little "Tailoring" to work - get tick-over volume down.

Anyway, after much investigation trying various test components, I settle for 10k ohms in series with pin (5) the MAF output signal. Lovely, just the job. However my tinkering around the MAF has been going on for about a week and although the alarm indications came up yesterday, I made no connection with them and the MAF as the car/engine continued to respond nicely to my tests, getting better, then worse, then finally better as I swapped components in and out.

So earlier today, having settled on the final value, I phone my local garage to book the car in to have this problem investigated. At the same time, I post for any help in trying to understand why I now have these failures.

To which, a prompt response points me in the direction of the MAF, with the prospect of it having failed at worst. However, was I being sent - up? What could possibly be the connection between the Hill Start handbrake function, the ASR, the VDC and the Fuel Gauge?

Feeling a bit of an idiot, I go out to the car - having just got back from the garden centre - and do as was suggested by bazzbazz, disconnect the MAF plug, give it the once over and firmly plug it back into the element.

Key - in, depress the clutch and press the starter button. Bingo!!!!!!!!!!!!!! The logic is lost on me, yet another mystery surrounding this enigmatic car.

But, none the less grateful to bazzbazz for his insight - top man! One more issue ticked - off the list. Car is now running very much quieter than when I started all this malarkey. Just marginally noisier than a standard 3.2JTS. No resonance, sporty character to the exhaust system - right across the revs - Alfetta 3.0 like. Bags of pep on the throttle. In fact it is so different - I am persuading myself, rather than cancel the garage, to give my new boxes another chance. If they work, I am going to be one very, very happy bunny.

Thanks again Bazz!   
   

[Colin Edwards]

When I had ASR/VDC/Hill Start issues the root cause was failure of the brake switch, or more to the point, poor adjustment. 
A simple resetting of the switch position cured the issue.

[bazzbazz]

When I had ASR/VDC/Hill Start issues the root cause was failure of the brake switch, or more to the point, poor adjustment. 
A simple resetting of the switch position cured the issue.

Yes, but the key indicator here was in addition the fuel gauge crashing to zero.

[Ascari32]

Well, true to form, things aren't as simple as it seems. Bazz pointed me in the right direction and that was that - or so I thought.

It was pure hypothesis about increased air flow due the changed valve timing and it seems a reasonable one at that. However, the ASR/VDC, Hill start and fuel gauge failed again. So further investigation was needed. Bazz is absolutely spot on wrt the MAF association. However, in reducing the current in the output to the ECU, I prompted a loop - sense fail. But the fact that I could reduce the "Power" in the tick - over, by trimming the current indicated air flow was affecting the ECU's ability to set the correct air fuel ratio. So I am on the right track. Just I can't trim the output of the MAF to adjust it, and expect the ECU not to display these failures.

Although the engine runs well, one cannot drive around with these failures permanently displayed on the dash. Although, it has to be said, with the 10k ohm in the output, the tick - over became the same volume as when I disconnected the MAF connector.

So, it seems I am being drawn towards remapping, which is not something I would willingly choose to do. The new Volvo XC70 senor is working brilliantly but the idle airflow is still sufficient to cause an output from the sensor, which it should not. This not only affects the tick - over, but the overall economy, given on lift of, fuel injected should fall to that which it is at idle.

So as an alternative, I may try to modify the flow characteristics through the MAF Venturi tube, or even change the whole of the inlet ducting. I shall have to do some more research/testing in the hope there may be some clues on how to achieve it, by way of a different MAF Venturi or reducing the airflow through the internal Venturi, in which the element sits. Essentially, the MAF body is a Double Venturi, the smaller enclosing the sensor, whilst it is located in the main body.

There must be a solution to this problem, even if it means a complete re-work of the inlet ducting. Just not yet thought too deeply about how to achieve it. The problem seems simple, yet the solution much less so.

Hey! Ho! The project goes on! Both fascinating and frustrating. Would I want it any other way? Probably not. Simple things aren't projects, they are just routine - and pretty boring to boot!

[Ascari32]

Hi!

Well given I started this thread, it seems only right that I should close it out, unless of course anyone else has something to add. Quite pleased that I gave sufficient detail in the title for BazzBazz to point me in the right direction. Given I was experimenting the with the MAF of my 3.2 JTS, it just tied in nicely and from then on things fell into place. Meaning, there was sufficient evidence to persuade me my outstanding problems revolved around the MAF output signal.

My current thinking is, whilst the Butterfly (Throttle) was closed, the MAF output voltage did not correlate with the conditions for proper idle and so the ECU was still reading the manifold lambda probes and attempting to set the AFR, despite both the inlet and exhaust VVT Solenoid Valves being in their "Default" positions, ie., inlet camshaft, fully retarded; exhaust camshaft, fully advanced. Hence the "Audibly Powerful tick - over at 750 rpm.

It is clear from the Bosch Data Sheets, the devices which have the greatest Kg./Hr. flow rates, do not specify and output voltage at the lower end, whereas, MAF elements, clearly intended for lower capacity/less powerful cars do! And because my original element was producing an output voltage, but behaving normally in every other respect, I am convinced it was the wrong element all along.

With the increased flow rate due to cross - flow/PVO, which my Colombo Bariani Camshafts introduce, an output voltage was being created which fooled the ECU into continuing to read the manifold lambdas, and attempting to set an Air Flow Ratio appropriate for minimizing emissions. This; I believe, caused the Lambda output signal (voltage) to induce the ECU to modify the fuel metering to the extent that it went beyond the range which could control emissions. Hence the Engine Management Code failures.   

The element now fitted is a 98660612501, AKA 280 - 218 - 055, which; as it transpires is fitted to 911 Porsche 3.8/4.0 Litre Turbo's and Ferrari 599 GT. This according to published details is also fitted as standard to the 3.2 JTS, although Alfa have gone to great lengths to disguise the fact.

None the less, the engine is now performing beautifully, particularly at Idle where one would be hard pressed to believe it is the same car as before the element was changed. Tick - over is particularly quiet now and the engine has remained free of any management failings/codes. I have concluded, the MAF element which was originally fitted was not the correct device, raising suspicions about some aspects of engine maintenance, prior to my purchase. However, the engine in the car now is a fully balanced and modified Brera engine, with cam, exhaust and header modifications. The Alfa rear boxes remain fitted but I shall soon be refitting the Ascaris. given I now have confidence that they will perform better than hitherto.

Thanks again to Bazz for a very swift response to this issue which saved an awful lot of time and grief. It would have taken me considerably longer to resolve this issue, had he not picked up on it very quickly. Particularly when he intuitively linked all the elements together.

Cheers.

[bazzbazz]

One is glad to be of service.

[specimenX]

I'm not sure where you have gathered the published details for MAF inserts( i suspect chinese site) as  0280218055 is not the correct MAF insert fitted to 3.2 JTS. The 3.2 maf insert can be found on engines with less than 75Kw output. You could always contact Bosch for accurate information, in the past i've found them very obliging.

[Ascari32]

Well, it really is a question of what to believe, particularly when it comes to anything on the internet.

The response curves for the 2.0, 3.0 GTV and the 008 are taken from Bosch data sheets. So too the "421" which is the highest rated I could find. I could not find anyone who could supply it. Also, the Porsche is no longer available from them. But I was given the 98660612501/055 as direct replacements.

I have contacted Bosch and they were far from helpful, suggesting I speak with the manufacturer - Alfa, suggesting to me, the precise details were exclusive to Alfa. And of course Alfa won't disclose any information beyond selling me a replacement, at their ridiculously over inflated price.

No matter, it was the 98660612501/055 I had been looking for which I am informed by several sources is the correct one for the 911 up to 4.0 litre. Also quoted for the 599 GT. And the 3.2 JTS.

It would not surprise me that this element has been "Tweeked" for Alfa as their valve timing creates the need for a very fast response at the bottom end. That would tie in with what you say of engines up to 75 kW., which is evidenced by the much more acute slope of the lower Kg./Hr. elements for smaller capacity engines - as per Bosch data sheets. Indeed I have written, "The Alfa Insert response is probably more acute than that of (1) of the Bosch data sheets".

Essentially there is little difference between all of the devices I have mentioned. It is just the way they are aligned that differentiates them. With a calibrated source, I could align them my self to match the engines characteristics.

None the less, I am happy with the 055 performance, both because of the super smooth idle, which I confess seems unusually subdued for a sports system, and the really crisp way the engine responds to the foot. It, undoubtedly will not be bang - on, but until I get it on the Dynamometer, I won't know precisely how far it may be out.

The important point being, with such dramatic changes to valve timing, it required, in my opinion, a gentler Transfer Charcteristic. With the Turbo of the Porsche doing all the work in shifting the intake air, I reasoned the response of the MAF would be much less acute.

This appears to be borne out as my SS cat, Autodelta headers and in particular the CB cams will create much higher flow velocities, sort of mimicking what a Turbo achieves. Cruise control is very smooth in the way it maintains the speed setting, with very fine interventions an economy is better than I hoped for, although unable to do further testing due to lockdown restrictions.

Yes, I do believe she is still a little rich, but she was on my last Dynamometer  run, with the same ECU. And I am impatient to try my Ascari back boxes again. However, "Slowly, slowly, catchee monkey". There is plenty of mileage left in this project to keep me entertained for some time to come. And Although I set out principally to get engine temperatures down, I think I can say, I have ended up with a pretty quick motor. And yes, I still want to fit a Holden badge!

[bazzbazz]

And yes, I still want to fit a Holden badge!

THE HORROR! 

[specimenX]

Well the simple question is .. What is the part number of the MAF insert you had orginally prior to all the experiments?

[Craig_m67]

Well the simple question is .. What is the part number of the MAF insert you had orginally prior to all the experiments?

I am sure that Ascari32 is aware of the MAF that was originally installed in his vehicle.   If you read any of his posts, it will become apparent to you that he has made a number of modifications and is looking to improve upon what was spec'd by Alfa.

Might I suggest you start another thread for arguments, requesting if you want the five minute or full half an hour. 

[Ascari32]

I said, nothing was ever going to be easy - but Hey Ho, yet another post cat alarm.

The performance of the Porsche MAF insert is very good across the range and the exhaust sound at tick - over is very subdued, by comparison to what it was just after the exhaust system changes. But failures do keep popping up.

Ignoring this, for the time being, an error does exist; even were the MAF a perfect match, insofar as with the Colombo Bariani camshafts the induction stroke is now a full 180deg., where hitherto as the inlet did not open until 11.5deg. ATDC it only amounted to 178.5deg.

The difference being an increase of 6.44% in potential air flow into the cylinders. Given air is swiftly moving through the inlet tract, courteousy of a 23.5deg. PVO, the relative effectiveness of this is substantial.

So I always believed, there would be a need to add a correction factor to the MAF output signal (voltage).

By simple trial an error, the output of the MAF: all the elements I have tested, has been reduced by way of a potential divider network between the output signal - pin 5, and the input to the ECU. I chose a total resistive value of 5,000 ohms to ensure this network would not load the MAF and drag the voltage down. This was convenient as at a peak output voltage of 5 volts, 5k ohm would result in 1 milliamp output current. The output of the MAF is low impedance and the input to the ECU is high; I believe, so the system should tolerate what amounts to very little extra loading.

By calculation, a 330 ohm resistor in series with 4k67 ohms, across the MAF pin 5 and pin 3 reduced the output signal (voltage), to a pretty close approximation of 6.44%:actual error: 6.6%, so .016% discrepancy is not bad.

But the engine is not as happy with that value as it is with 266 ohms in series with 4670 ohms - the output to the ECU being taken from the junction of the 330/266 ohm resistor and the 4670 resistor, the bottom end of which goes to pin 3: ground/0V. This amounts to a correction factor of 5.39% It may well be worth testing a lower value than 266 ohms.

I do not understand why this is the case but there is so much that I still do not know about this engine and in particular the software/ECU, I can only go with what evidence comes out of my tests. It may have something to do with improved Volumetric Efficiency, which a change in valve timing has generated.

It is true, millivolts output signal change can make a tremendous difference to the AFR and it will need to be trimmed eventually with a software recalibration. But given, I seem to be in the right region, such that I can provoke code failures and clear them, with small changes in value, I am not unduly worried, as long as I do not run the engine lean: which was always a worry despite my believing it was on the rich side.

Economy appears to be better than anticipated and a step - change occurs much more obviously at ~1500 rpm with the 266 ohm resistor, than with 330 ohms, whilst the exhaust system - Alfa Boxes - seem less laboured. Ideally, a diode in series with the output of the MAF causes the ECU to run the engine as if the MAF plug was disconnected. But the forward voltage required to overcome the internal junction voltage of the diode creates a flat spot which cannot be overcome. But the difference with the 266 ohm is not so different and persuades me I should try the Ascari back boxes again.

The car is quick - very quick! So, Air Fuel Ratios across the rev range; given I can detect no flat spots whilst accelerating, cannot be too far adrift from where it ought to be. But with this Pandemic and the need to do more tests, it will be some time before I can get her in for dynamometer tests.

Footnote:-

As this engine is direct injection, at tick - over and certain periods, fuel is injected at, or near TDC, it seems logical to assume there is ample time for the ECU to accurately meter the intake air sensed by the MAF. So despite my initial concerns, an accurate AFR should be possible.

This being the case, the air flow through the inlet manifold at the beginning of the induction stroke will suffer much less inertia and greatly improve VE. So, it may well be that any fuel metering needs a compensation factor applied to take this into account.

Perhaps this why I am seeing an improvement in engine behaviour with the lower value resistance, ie., the difference between cylinder fill and overfill, due to the velocity of intake air causing compression of the charge air, before the inlet valve finally closes on the compression stroke.

Just a Hunch!

[Ascari32]

Hi Kierenc,

Nice to know you are pursuing this. Although I have always felt the Spider was a "Bit Large", my affection for it has continued to grow. So much so that I genuinely believe it to be a car that will still turns head 30 years from now. And the Q4, from my experience with my 159 is second to none - forget your Audi's, this system is the Bees Knees.

The engine however, has never been right, IMHO, but has the potential to be great. The Block is a masterpiece and the fact that it will continue, albeit with some changes, to be produced until 2026 speaks volumes for it. I am convinced that will not be the last we will see of it either. With the swing towards "Environmentally" friendly transport, there will not be the impetus to come up with new "drawing - board designs", so this engine could be pressed into further service beyond 2026.

However, back to your Spider!

I shall try to deal with your questions, not necessarily in the order you asked and I shall add a little by way of cautioning you about the overall cost.

The MAF issue has and continues to occupy quite some time. However, these issues revolve around code alarms and not engine performance. As you would expect, making modifications to the MAF, as I have done, is bound to affect performance. But they have been done; and continue to be done, to see how much more can be gained from my engine modifications. And also, I confess, to defer a visit to a good software company for remapping. But regardless of the issues surrounding the MAF, there is no question about the tremendous difference between my engine now and as it was prior to modification.

In every respect, I consider my 159 to be "Sports Saloon" and the engine, given I have exclusively owned Alfas for over forty years, performs better than any I have owned. It does not have the charisma of my 2.5 Alfetta GTV, but it has a balance which is extraordinary for such a big car. It can never be as great as the Busso V6, but it is better. The flexibility the VVT System brings to the engine can never be overstated. And while it does not sing the same song as the Busso, it's power is expressed in the exhaust note much more forcefully. It never runs out of breath as some variants of the Busso do, although the Busso can be made to perform extraordinarily well for such an old design. But, one mustn't detract from Busso's achievement and I still have my 3.0 GTV after all these years, unwilling to come to terms with parting with her.

It has been quite an exercise in resolving the MAF issues. But, I believe the Porsche MAF insert, 98660612501, AKA 0280218055, AKA 0280218192 suits the engine and as such it will remain my final choice. My original element, whatever it may be, is history and will remain so. It is also reassuring that the clip of the SW with C.B. cams and Brembo's has been well prepared after considerable money was spent on it and no doubt performs really well, particularly given the expense on the exhaust system, let alone all other components.

I recently posted on the Aussie site my latest thinking wrt the MAF and I now believe I have got my head around the issue of flow rates/AFR better than hitherto. The potential divider network using 2670 and 266 ohms gave noticeable better performance than the 330 and 2670 ohm resistors. Adjustments, I now realise, need to be incrementally small as one can go through the optimum point without realising it. And when all is said and done, I can always fit the Supersprint tail boxes to quieten the exhaust system a tad more.

It seems strange to say, but in truth the MAF issues have been at least the cheapest aspect of all the work which has gone into the engine. I firmly believe the Manifold Cats are real killers of this engine. I am informed by Autodelta that their headers can be fitted without the removal of the engine. However, as my spare Brera engine was being rebuilt it was not an issue for me. There will be a marked reduction in engine temperatures alone if only their removal is undertaken. But, as Supersprint pointed out the secondary cat under the car, being Ceramic, have a lower operating temperature and the catalytic wash could be stripped and cause blockages due to exhaust gas temperature after the Man Cats are removed. Particularly if valve timing is modified in the way that the C.B.'s do. One commentator has stated the angles are very much in the same territory as his Ferrari! Certainly, the sound they generate is glorious.

However, the work I have been doing surrounding the MAF has now led me to believe there is no issue with the Colombo Bariani Exhaust Valve Timing. My initial concerns were wrt the way the air is metered through the MAF with such a large PVO and the fact that the C.B. inlet is now open 0.5deg. BTDC, thus giving a complete induction stroke from TDC to BDC - volumetric efficiency being improved further given the inlet also closes later: compressive action of the rising piston upon the fast moving inrush of air through the inlet manifold, ably assisted by the massive valve overlap/scavenging and the Supersprint exhaust system, with sports cat.

But given at tick - over and under certain conditions the fuel is injected at, or around TDC on the compression stroke, the ECU has ample time to read the MAF flow rate and set the correct AFR, in conjunction with the wideband lambdas and certain other parameters. And I believe the C.B.'s will also afford a greater degree of accuracy of AFR - when the fuel maps are corrected, which will extrapolate as increased power output.

However Colombo Bariani confirmed to me, changing just the inlet camshaft would net an improvement only fifteen percent less than if all four camshafts were changed. With this in mind, whilst not maximising gains, considerable money could be saved with only a two cam (inlet) set up.

It could actually be cheaper as peculiarly Alfa have used hydraulic lifters of different heights on the inlet and exhaust camshafts, inlets being 34mm. and exhausts 37mm., if my memory serves me correctly. So fitting exhaust lifters to the inlet side, a regrind of the Alfa Inlet camshaft may well be possible. to achieve either a higher lift or a longer duration, whilst the Alfa Exhaust camshaft remains unchanged. And the exhaust lifters are more readily available.

Yes, the Colombo Bariani Camshafts are expensive and their performance is very much dictated by accuracy of valve timing. With this in mind, it is really essential to renew the timing chain system. I think you can see the direction this is heading. Combined with the very first issue I addressed wrt this engine, the tensioner system is not sufficient to maintain accuracy due to poor oil flow/pressure distribution across the block. Were I to do nothing else to this engine, I would definitely modify the oilways with supplementary lines - again. This, aside from improving chain tension, greatly improves the oil feed to the VVT System and makes a marked difference to its speed of operation.

Another problem with is engine is its relative low sump capacity. It is designed around four litres capacity but the return of spent oil from the system is very slow and the oil pick - up snout in the sump is quite high above the sump floor. At high revs, the level in the sump can dramatically drop and, particularly when the car is moving laterally, the pick - up can become exposed and the bearings suffer oil starvation. The latest version of this engine has a massively redesigned sump of much greater capacity. They have also included baffle/swage plates to ensure oil is always moving across the face of the pick - up, whatever direction the car is traveling in. In addition, they have extended the windage plate across the full length and I believe they have redesigned the return ducting for oil from the cylinder heads, away from the rotating crankshaft journals.

Simple modifications to the VVT Solenoids and the camshaft position sensor on the rear bank exhaust camshaft improve the accuracy of timing further. But, looking back, it seems such a daunting prospect. In truth, the mechanical side was very straight forward, especially given I had some fantastically good people involved - Scholar Engines, Fast Test, Brian Randal, Kevin Johnson, Supersprint, Autodelta, Mauro Bosio and Colombo Bariani, and numerous others who helped source parts.

Kierenc, you are about to undertake a project which will cost a lot of money. And I fear, you will not be satisfied with "Half Measures". That being the case, a spare engine may be the way to go, so you can progress it in an orderly pace and spread the cost over a longer period. But if you choose to go down the modification route, I would start with the Manifold cats. According to Autodelta, that will save about 8 bhp in losses, but your engine temperature will drop dramatically and it will stop destroying its oil. Intake air density will increase as temperature drops so actually it may well be worth 10 - 12 bhp.

I don't think accuracy of valve timing can be achieved and sustained long term unless the timing chain system and vvt's are addressed, which means "Oil Way Mods". Beyond that, C.B. cams are still high up the list, particularly as they can be reprofiled for even more performance. But, oil flow/pressure needs to be improved to get the best from the C.B.'s. Unless Mace have moved the Lobe centres I cannot see them being even better than Alfa's stock cams. Their blurb implies the cams give a pleasant exhaust sound but say nothing of increasing power. You pay for what you get and Mace are cheap, I suspect because they are more cosmetic than performance related. If the lobe centres stay the same - which I believe they do, and duration is less than Alfa's, then that won't generate PVO.

I hpe I have covered your questions. However, you can always PM me if there is anything you feel I may have omitted.

Kind regards,

Further to my above, I started this project with little knowledge of what I was letting myself in for. The improvement to the lubrication system I felt worthwhile but at that time had not anticipated the failure of my engine, which led on to the Brera rebuild.

However, knowing what I know now, would I undertake to do it all over again?

The answer to that question is, most definitely, YES. Having been back on the road again for a year tends to diminish the difference between my car now as opposed to how it was. So I must get to drive a standard 159 or Brera, which would bring home just how different the two are. None the less, the car feels right both for it's size and performance. It sounds so much sweeter, melodic even. But I understand the real cost of achieving this and couldn't recommend it to anyone that did not view the a car with the intention keeping it for a very long time.

Logically speaking, removing the man - cats and fitting Autodelta's would be a start. Removing the secondary cats and fitting a sports cat - Supersprint. - and their centre section could be a good second move. Then replacing the rear boxes, so that the whole system was much more free flowing, not having Alfa's central resonator.

A marked improvement would be achieved with these changes alone. which may then whet the appetite for replacing the camshafts. At which point, I believe it essential, to maintain valve timing accuracy, the timing chain system should be replaced with the uprated Mace system, whilst oilway and vvt modifications can be incorporated - without engine removal, to ensure one gets the best from the improved breathing and increased power the camshafts will bring.

It may not to be everyone's liking, preferring not to believe there are issues surrounding the oil flow/pressure, but throughout the time it has taken to rebuild this engine, so much more has come out of it to reinforce my belief that this issue alone is an overriding factor which limits how well this engine can perform.