Engine runs bad when warmed up

[Gerard van Santen]

The engine runs OK when cold but as soon it has warmed up, it looks like it is has lost one or two cilinders.

I ran my codes and first I got a 3 (manifold pressure regulator) and an 18 (ignition timing adjuster). The second time after resetting the ECU I only got an 18.

Can somebody help me out?

 

[Larry Bastanza]

Hi Gerard,

The procedure to test this is on 11-60 in the on-line manual. It seems to be a hard failure since you get a code after reset. I would check the adjuster as desribed and also carefully look at the wiring. If the timing is way off, this may account for poor running when warm.

Also, is the CTSC installed now, or is this a stock engine configuration?

HTH,
LarryB

 

[Gerard van Santen]

Hi Gerard,

The procedure to test this is on 11-60 in the on-line manual. It seems to be a hard failure since you get a code after reset. I would check the adjuster as desribed and also carefully look at the wiring. If the timing is way off, this may account for poor running when warm.

Also, is the CTSC installed now, or is this a stock engine configuration?

HTH,
LarryB

Hi Larry,

I have changed the complete control box for another one. The symptons are the same. But I don't get code 18 anymore. I get a 31 on the TCS light now.

The CTSC is installed and it seems to work fine.

 

[Larry Bastanza]

Can you check the timing? Also maybe you should look at the wiring for the speed sensor too. Since the TCS may be dependent on that.

HTH,
LarryB

 

[Gerard van Santen]

Can you check the timing? Also maybe you should look at the wiring for the speed sensor too. Since the TCS may be dependent on that.

HTH,
LarryB

If I disable the TCS? Could that be an option?

 

[Larry Bastanza]

I would try it, but it is odd if this would cause rough running when warm. It may tell you something about the problem though.

Since we are not sure if the TCS is actually involved in the rough running, I would disable it, then the next step is to look at the timing as well as the fuel pressure, since the Comptech is installed, the RRFPR should be checked and adjusted to keep the A/F ratio correct.

With the CTSC fuel pressure is the main adjustment.

HTH,
LarryB

 

[Gerard van Santen]

I disabled the TCS, changed the GruppeM air filter for OEM. Cold the engine runs fine. Warm I still get code 18 and have a rough running engine.

Tomorrow I will check the fuel pressure. But how can I check the timing?

 

[Larry Bastanza]

Page 23-91 in the online service manaul shows an inductive pickup type timing light on a service loop near the ignitor. It shows checking timing at idle. I am pretty sure max advance is 28 degrees BTC.

HTH,
LarryB

 

[Gerard van Santen]

Found the problem!!

Yes...

I have located the problem. It seems to be a fuel pressure related problem. With a cold engune the ECU sends more fuel to the injectors than while the engine is warm. That's why it was running OK with a cold engine and was running lean when warm. The ignition timing adjuster retarded the ignition timing to avoid pinging.

I came to this conclusion when I connected the wires for the volt doubler. I had enough fuel pressure now. The engine ran fine. After idling the engine for a quarter of an hour I restored the wiring of the volt doubler. No problems occurred.

So I have a problem with the fuel delivery to the cylinders. I now think I know where to look for.

Larry, do you agree?

 

[Larry Bastanza]

Yes,

I agree. Do you have a good idea of the fuel pressure vs. boost that the RRFPR should give you? I do not have the numbers off hand. Hopefully someone can provide them here, or post the question in the Forced Induction forum and you will have your answer quickly.

Good Luck,
LarryB

 

[Gerard van Santen]

Yes,

I agree. Do you have a good idea of the fuel pressure vs. boost that the RRFPR should give you? I do not have the numbers off hand. Hopefully someone can provide them here, or post the question in the Forced Induction forum and you will have your answer quickly.

Good Luck,
LarryB

Larry, thanks for your supprt. I will look for the right numbers now.

Gerard

 

[Gerard van Santen]

Engine seems to run fine. But I see a code 41 now. The front oxygen sensor. I changed the sensor for another one. The code remained (I did reset the ECU first).

I hear some pinging above 5krpm. So I tried to give as much fuel pressure as possible by adjusting the Vortech SFMU. The best I got was a 41 PSI at idle and about 90 PSI WOT.
I wasn't able to do a dyno yet, but the fuel pressure I get should be enough

What can be wrong now?

 

[Larry Bastanza]

Hi Gerard,

I think your fuel pressure is about right now, if I recall. I think you actually did not get to check the timing, correct? I think it would be important to make sure if it set correctly at the baseline idle which is 15 degrees before TDC @750rpm. Then you can check for max advance at 28.

Also the 41 indicates the ECU is seeing a bad 02 sensor heater. This is either an open wire that feeds the heater curcuit or the sensor heater is bad.

Page 11-32 in the service manual has a very easy procedure to test the 02 sensor heater curcuit. It is just a heater coil inside the 02 sensor, so you can check it for resistance. It is possible you have a bad wire/connection. Make sure you check inside the gray connector housings(by the valve covers) that you do not have a pushed in male pin, making a bad contact, this is common.

In regard to your pinging, with the 41 code I think the ECU is in open loop all the time, so until you resolve the heater issue, I would not spend too much time on that. Once the ECU thinks all is well, maybe your pinging will disappear.


Good Luck,
LarryB

 

[Gerard van Santen]

Hi Larry,
I didn't check the timing yet. I have changed the O2 sensor for another one with no results. I will check the connectors tomorrow (it is late in the evening now).
Thanks Larry

Gerard

 

[Larry Bastanza]

Gerard,

Also make sure the 02 sensor is good using the procedure with a multimeter, it is possible you actually have two bad sensors.

HTH,
LarryB

 

[Gerard van Santen]

Gerard,

Also make sure the 02 sensor is good using the procedure with a multimeter, it is possible you actually have two bad sensors.

HTH,
LarryB

I'll do. Thanks.

Gerard

 

[Gerard van Santen]

Problem solved...

I found out what was the problem with the front O2 sensor. It seems to be that the cable of the sensor was to close to the front header. It melted and that caused code 41.

I just did a testdrive and everything seemed to be as it should be. I didn't hear any sign af pinging anymore. Fuel pressure was OK up and down the rpm range.

A Dyno is the next thing to do. I am curious about the A/F ratio.

Larry, thanks for your help.

Gerard

 

[Gerard van Santen]

I thought the problem was solved. But the next day the same malfunction occurred.

I changed my spark plugs with one degree colder ones. Changed the coil packs again. Even changed the TW- and TA-sensors. Nothing worked out the way I hoped.

But with the help of Cees-Jan we found out what was really the problem. It seemed to be the big connector on top of the gearbox.

I always thought that this connector had something to do with an automatic gearbox and that it had no function in a manual one. It seemed to be topped off. But now I know that it has to do with the coil packs. The coil pack on the third cylinder (front row) only got 10 volts. The others got 12 volts. So the engine ran on 5 cylinders.

The connector looked fine but after cleaning and using some connector cleaner it all worked out perfectly.


This is the connector.. (sorry for the bad resolution. I made it with my cell phone).

 

[Cees-Jan]

This is how we located and fixed the problem, we used a CO-meter to analize the exhaust fumes.The apliance can measure the %O2, the %CO the amount of parts HC(=petrol not burned)and calculated lamda.

At first we see a lot of CO 2.5% instead of 0.49%,this indicates a rich mixture.
We also see approx. 2000 ppm HC indicating a lot of not burned petrol.
Final reading was 5% O2 in the exhaust.

This gave is the certanty that one (ore more) cylinder was not igniting and therefore is feeding O2 and fuel into the exhaust.

Now we started disconnecting each coil pack, one at the time to determine which cylinder was bad.Found it instantly and exchanged the coilpack, no go,same problems.

Now we started measuring, black/yellow wire should deliver battery voltage to coilpack, only gave about 10 volts.
It turned out that all six coilpack wires are conneected to the connecture in the above picture(that is my hand by the way).

We could not see anything wrong, but after cleaning and reconnecting the voltage was correct and all problems solved.


TIP: IF YOU SUSPECT DEFECTIVE COILPACKS TRY CLEANING THIS CONNECTOR!

 

[j14nsx]

Did this connected come with Guus' engine, or does it remain from the wiring from the old engine? If so, would this have anything to do with the failure of the first engine?

 

[Larry Bastanza]

Cees-Jan,

Very nice find!! I will remember this one. Also I am interested to hear a response to j14nsx's question.

Glad it is truly solved.

Thanks,
LarryB

 

[Cees-Jan]

All wiring and connectors are Gerards, The hart, the turning parts came from Guus his NSX.

Gerards engine blew because of a failure in the krank pully which broke the plastic timing belt cover.Result timing of and pistons hit the valves.

 

[Cees-Jan]

Still have one "problem"with the car: A very wide white line after the windscreen.....


Turned out to be Gerard smiling ear to ear