89 M100 Turbo Wont run past 3000 rpm hits a brick wall

[kevrob]

Where to start... bought the car with faulty MAP sensor, corrected and fitted new CAS and ATS... then Fuel Pump fails, New Pump and Filter, then an injector went out of spec , changed Coils, Regulator and new Injectors. All set to go ! Now car wont rev past about 3250 rpm just as the boost should be really picking up and the car flying along.
No engine faults codes at present, have just logged an elan scan run which I hope maybe someone might be able to help with.
I found a similar thread whereby someone had virtually the same fault and so ive ordered a new CAS again

[Rambo]

Have you done the paperclip/self diagnostic check?

If so, had you had a CAS fault, it would have shown up as error 41. Why do you think you need another expensive CAS? They are pretty bomb proof apart from o seals and becoming noisy.

[KenS]

Has the static timing been set up while in Service mode (ref the WikiLEC)? Needs a LEC expert to interpet the log file, but to me it looks like the 'spark advance' may be indicating a base timing of around 10 degrees instead of the required 16 degrees. If the engine is retarded, this may explain why the 'knock count' is high/odd ? I am sure someone will come forward with a more confident appraisal of your log file!

[Tuga2112]

just another random idea... the TPS may be set incorrectly and the computer just never thinks your putting the foot down enouhg

[kevrob]

Have you done the paperclip/self diagnostic check?

If so, had you had a CAS fault, it would have shown up as error 41. Why do you think you need another expensive CAS? They are pretty bomb proof apart from o seals and becoming noisy.

Well the new CAS has not worked, so back to the drawing board..

[kevrob]

Has the static timing been set up while in Service mode (ref the WikiLEC)? Needs a LEC expert to interpet the log file, but to me it looks like the 'spark advance' may be indicating a base timing of around 10 degrees instead of the required 16 degrees. If the engine is retarded, this may explain why the 'knock count' is high/odd ? I am sure someone will come forward with a more confident appraisal of your log file!

Set the static timing in service mode and lines up with previous marks on the CAS assembly, there is a bit of flutter on the timing wheel so that led me to think that the CAS was at fault but no.

[kevrob]

Have you done the paperclip/self diagnostic check?

If so, had you had a CAS fault, it would have shown up as error 41. Why do you think you need another expensive CAS? They are pretty bomb proof apart from o seals and becoming noisy.

Yes have done the paper clip test no faults showing at present, i was mainly going by a previous post i found and the fact that the timing marks flutters about a bit on the strobe.

[Tuga2112]

have you checked the engine manual. ? theres a section about diagnosing issues. may be worth checking in the manual if theres any special event related t how the engine runs that happens around 3k. may point you in the direction of some specifc sensor id hope

[KenS]

just another random idea... the TPS may be set incorrectly and the computer just never thinks your putting the foot down enouhg

The log file for the TPS & engine RPM shows that the TPS sensor voltage doesn't reach the 4.0V that would be expected for full throttle, only attaining 2V and revs reaching 4000.



For reference an random example of a log file for a different car shows TPS reaching the 4.0V level and correspondingly the rpm achieves 6500.


So Joao may be correct? May be worth trying to devise a method of measuring the voltage at the TPS. There is some info in the Engine Management Manual Section EMK.4 page 38.

[Tuga2112]

if you have elanscan. you can read TPS voltage with the engine not running. and just put the foot down and see that it reads.

[chrisP]

If you pull back the rubber cover on the TPS, you can use a multi meter to test the voltage. Ignition on, but engine not running, you can move the spindle and see what results. I cannot remember the wire coding though.
Chris

[dapinky]

Probably connected to the above, because the numbers correlate..... but if you look at 'Throttle' as the Y axis, it only goes up to about 45% - which is about what we'd see with a 2V TPS signal....

.... so either there was no 'foot down' driving during this recording, possibly due to the fault, or it isn't set up right.

Both throttle and TPS are easy to see and set with Elanscan - just connect it with the ignition on and start talking.....

At rest, the throttle should read 0% and the TPS should read 0.4V........ slowly operate the throttle pedal and watch the numbers increase to 100% and 4.0V.

If it doesn't get to 100% it indicates either an obstruction to the pedal (thick mats?) or a badly adjusted cable - there should be a quite slack cable, but still able to reach 100% on the pedal...... if it doesn't then have an assistant under the bonnet open the throttle by hand whilst your foot is on the pedal, and see if it then goes to 100% (it should!) and if not, then there is a problem with the mechanism... however, I have never seen one where it requires anything other than a slight adjustment of the cable.

I certainly have never known a cable so slack that it would only give 45% throttle.

The TPS adjustment is by way of 2 M4 setscrews on the TPS into the housing - slacken the screws (or remove them and throw them away, replacing them with new stainless M4 ones!) rotate the TPS unit until it reads 0.4V at rest, tighten screws. Open and close throttle by hand to check it reads between 0.4 and 4.0 volts (it may take a while to get it right - mines took about 5 or 6 adjustments to get it to return to 0.4.... it seemed okay until I opened it fully, then returned to either 0.38 or 0.42..... but I got it in the end.

[KenS]

Its interesting that the car needed a new MAP sensor, since this connects to the same 5V reference used by the TPS sensor. The Engine Management Manual says 'An internally shorted MAP sensor can pull down 5V REF voltage (to the TPS)'.
Once it is known if the TPS signal is not corresponding to throttle position, then the problem could be TPS sensor (or wrong type fitted) or corrupted reference voltage sent to the TPS. That 5V reference could be measured with a voltmeter at the TPS.

[kevrob]

just another random idea... the TPS may be set incorrectly and the computer just never thinks your putting the foot down enouhg

The log file for the TPS & engine RPM shows that the TPS sensor voltage doesn't reach the 4.0V that would be expected for full throttle, only attaining 2V and revs reaching 4000.



For reference an random example of a log file for a different car shows TPS reaching the 4.0V level and correspondingly the rpm achieves 6500.


So Joao may be correct? May be worth trying to devise a method of measuring the voltage at the TPS. There is some info in the Engine Management Manual Section EMK.4 page 38.

TPS is fine just checked goes from .38 to 3.99 I was only driving on the car on part throttle...

[kevrob]

Probably connected to the above, because the numbers correlate..... but if you look at 'Throttle' as the Y axis, it only goes up to about 45% - which is about what we'd see with a 2V TPS signal....

.... so either there was no 'foot down' driving during this recording, possibly due to the fault, or it isn't set up right.

Both throttle and TPS are easy to see and set with Elanscan - just connect it with the ignition on and start talking.....

At rest, the throttle should read 0% and the TPS should read 0.4V........ slowly operate the throttle pedal and watch the numbers increase to 100% and 4.0V.

If it doesn't get to 100% it indicates either an obstruction to the pedal (thick mats?) or a badly adjusted cable - there should be a quite slack cable, but still able to reach 100% on the pedal...... if it doesn't then have an assistant under the bonnet open the throttle by hand whilst your foot is on the pedal, and see if it then goes to 100% (it should!) and if not, then there is a problem with the mechanism... however, I have never seen one where it requires anything other than a slight adjustment of the cable.

I certainly have never known a cable so slack that it would only give 45% throttle.

The TPS adjustment is by way of 2 M4 setscrews on the TPS into the housing - slacken the screws (or remove them and throw them away, replacing them with new stainless M4 ones!) rotate the TPS unit until it reads 0.4V at rest, tighten screws. Open and close throttle by hand to check it reads between 0.4 and 4.0 volts (it may take a while to get it right - mines took about 5 or 6 adjustments to get it to return to 0.4.... it seemed okay until I opened it fully, then returned to either 0.38 or 0.42..... but I got it in the end.

There was no foot down driving only part throttle/// rechecked TPS and all good goes from .38 to 3.99

[kevrob]

Probably connected to the above, because the numbers correlate..... but if you look at 'Throttle' as the Y axis, it only goes up to about 45% - which is about what we'd see with a 2V TPS signal....

.... so either there was no 'foot down' driving during this recording, possibly due to the fault, or it isn't set up right.

Both throttle and TPS are easy to see and set with Elanscan - just connect it with the ignition on and start talking.....

At rest, the throttle should read 0% and the TPS should read 0.4V........ slowly operate the throttle pedal and watch the numbers increase to 100% and 4.0V.

If it doesn't get to 100% it indicates either an obstruction to the pedal (thick mats?) or a badly adjusted cable - there should be a quite slack cable, but still able to reach 100% on the pedal...... if it doesn't then have an assistant under the bonnet open the throttle by hand whilst your foot is on the pedal, and see if it then goes to 100% (it should!) and if not, then there is a problem with the mechanism... however, I have never seen one where it requires anything other than a slight adjustment of the cable.

I certainly have never known a cable so slack that it would only give 45% throttle.

The TPS adjustment is by way of 2 M4 setscrews on the TPS into the housing - slacken the screws (or remove them and throw them away, replacing them with new stainless M4 ones!) rotate the TPS unit until it reads 0.4V at rest, tighten screws. Open and close throttle by hand to check it reads between 0.4 and 4.0 volts (it may take a while to get it right - mines took about 5 or 6 adjustments to get it to return to 0.4.... it seemed okay until I opened it fully, then returned to either 0.38 or 0.42..... but I got it in the end.

There was no foot down driving only part throttle/// rechecked TPS and all good goes from .38 to 3.99

In service mode the idle increases by about 500 rpm is this normal?
what happens if you drive the car in service mode???

[dapinky]

The service mode just disables most of the sensors - so it will never perform properly, in effect, it enters 'limp home' mode and won't let you rev high or engage the turbo. It errs on the side of safety by over fuelling so as not to run lean and risk a melt-down.

The revs shouldn't rise when you enter service mode - they should be at 950rpm in service mode, and if it isn't then you need to adjust the throttle bleed in service mode to get it correct at 950 (preferably measured on ES not the tacho - which can be a bit awkward as you can't get a paperclip in to set it into Service with ES plugged in..... I got round this by splicing the 2 wires into the plug and connecting a switch in the glovebox, so shorting out the 2 wires with the switch enters Service, and ES can still be used.)

[KenS]

Oh, back to square 1.
Once you get the idle set-up, I think the base timing needs resetting (follow the WikiLEC base timing procedure which sets the IAC), the current log file does look like its currently around 10 deg btdc but at that high idle.:


If still no luck its worth capturing a new Elanscan log file, with some full throttle periods which may show something odd at the higher throttle values.

[KenS]

Good guide in the WikiLEC section for idle speeds:

wikilec.com/view/Tickover

[kevrob]

Oh, back to square 1.
Once you get the idle set-up, I think the base timing needs resetting (follow the WikiLEC base timing procedure which sets the IAC), the current log file does look like its currently around 10 deg btdc but at that high idle.:


If still no luck its worth capturing a new Elanscan log file, with some full throttle periods which may show something odd at the higher throttle values.

Thanks Ken, you weren't far out because I tweaked the Base Timing again this morning a couple of degrees but I will slow down the idle and have another go. Although its pretty much spot on at present 16btdc in service mode and out of service mode. I will do another run and nail the throttle to see what else if anything I can pick on the scan. This a real headache !