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R33 GtsT No power and backfiring after Cam Belt change


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Definitely don't parts cannon your way out of this. As a part of the cam belt service the CAS has to come off. I would look very carefully at the CAS and the bits that it interfaces with to verify that nothing is worn or has play. If for whatever reason it was binding against the cam drive that could cause the symptoms you're seeing.

If you're worried about plugs pull them and inspect them. It's not a modern car where pulling plugs is a massive ordeal so it's fine to put used plugs back in if there's nothing wrong with them.

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Hi All,

 

Still trying to get my hands on a CAS sensor. Seems people in my area are being a little quiet at the moment and the local get together has now been cancelled due to some BMW drivers getting too excited at the meets and ruining everything :<

 

Anyway, I've been tinkering and tried a new software that may be able to read the ECU. Unfortunately i've not been able to get it to work yet however it did make the check engine light do some funny things.

Out of curiosity I performed the bridge trick to get the code and it has now started giving me 3-4 knock sensor.

 

I reset the ECU and start the car, idle for about 30 seconds and check the code again. Knock sensor again.

 

As this seems to be a permanent thing but the engine sounds great I've looked into temporary bypassing the sensors to see if this stops pulling timing and dumping fuel. However I'm finding it difficult to do this.

I've checked the sub loom that has good continuity so I don't think it's that, maybe the main loom?

Checking forums I'm supposed to use a resistor between the knock sensor cable and a ground point. I used a 470kohm resister at the plug end and now at the ECU loom but I'm still getting the code.

 

Does this mean I'm not doing it correctly/incorrect resistance or is there other things that can cause code 3-4?

 

On a side note, I did see that the speed sensor wire at the ECU was broken so fixed that. Not sure if it's changed anything though.

 

Thanks.

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On 11/25/2021 at 7:19 AM, Skaith4224 said:

Hi All,

 

Still trying to get my hands on a CAS sensor. Seems people in my area are being a little quiet at the moment and the local get together has now been cancelled due to some BMW drivers getting too excited at the meets and ruining everything :<

 

Anyway, I've been tinkering and tried a new software that may be able to read the ECU. Unfortunately i've not been able to get it to work yet however it did make the check engine light do some funny things.

Out of curiosity I performed the bridge trick to get the code and it has now started giving me 3-4 knock sensor.

 

I reset the ECU and start the car, idle for about 30 seconds and check the code again. Knock sensor again.

 

As this seems to be a permanent thing but the engine sounds great I've looked into temporary bypassing the sensors to see if this stops pulling timing and dumping fuel. However I'm finding it difficult to do this.

I've checked the sub loom that has good continuity so I don't think it's that, maybe the main loom?

Checking forums I'm supposed to use a resistor between the knock sensor cable and a ground point. I used a 470kohm resister at the plug end and now at the ECU loom but I'm still getting the code.

 

Does this mean I'm not doing it correctly/incorrect resistance or is there other things that can cause code 3-4?

 

On a side note, I did see that the speed sensor wire at the ECU was broken so fixed that. Not sure if it's changed anything though.

 

Thanks.

If this is a two wire knock sensor you should verify that there isn't a short to ground. Also make sure you don't have a marginal connection by tapping the wires while you test their continuity. If you have solid contact with the terminals the whole time but you see resistance changing as you move the wires around it's possible that there's a break in the line that is just staying connected part of the time.

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Hi i had similar problem backfiring and knock sensor showing problems turned out my coil packs were mostly stuffed try firing up the engine with the coil cover removed and look at the coil packs with the engine running at night with no light and see if your coilpacks are are shorting to the engine mine were like a mini lightning show shorting out every where new coil packs and plugs gapped to 0.8mm and cured my problem is your car a series 1 or 2 if series 1 could also be an igniter prob your boosting prob could be the hose on the high /low boost controller hope this helps 

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Hi All,

 

Quick update. Still can't bypass the knock sensors so giving that a miss for the moment.

 

The car is a series 2 so simple coil setup. Wanted to check tonight but the car now won't start due to the fuel pump.

 

I'm now all colours of confused and think I'm getting way out of my depth here.

 

Today I had a bit more of a fiddle with the sensors by grounding them on the ECU ground and a few other things. no change. Checked continuity from the ECU cable to the sensor plug and all seems connected and getting good signal.

 

Went for a quick drive to my mothers today to say hi and when trying to leave, the fuel wouldn't prime again. nothing from the pump. The relay clicks but nothing.

I fiddled with the relay briefly and it came back so I went on. Later the same thing happened but took a little more trying but finally primed.

Now I can't get the pump to work at all. It's now very cold so maybe the temperature is not helping things?

 

This is my third pump as the original one that came with the car was aftermarket but sounded intermittent so I changed it with a walbro pump. That failed within 2 weeks so I went back to the old one.  By this time I had read up on the relay hotwire method to get correct voltage to the pump but I guess it was too little too late. That then failed and left me stranded. Ordered a 3rd pump, "quantum 340LPH pump" that has decided to stop today. I'm going to be checking wiring tomorrow however I'm now wondering if this could all be related.

 

To summerise:

 

Car was running okay, needed some leaks to fix and replace some consumables like the plugs etc however wasn't too bad.

Took it to the garage to replace the water pump as it was leaking at the bearing spraying water on the belts making them squeel.

As the water pump is behind the Timing belt I purchased a HKS kit with bearings to fit as well.

After getting the call to collect the car I immediately noticed hesitation when cold and no power/overboosting at high rpm. (boost would go up from 7psi to about 12 after the car felt like it bogs down so I don't think it's the ECU limiting fuel due to too high boost at first)

Took the car back and took the front end off again. checked all marks and all seemed fine. still no power.

Since then had the issue with the second fuel pump and replaced that with the new relay mod.

when mucking about with an OBD2 device the check engine light flashed so I checked the code and it came up with 34.

I don't recall this code when I first got the car back from the garage as it was just blinking 55.

 

I'm saving for coils and had some friends mention getting the fuel rails/injectors checked due to the pump problems.

Any ideas why the pumps keep failing if not a wiring issue?

 

Do you think I now have to take this to a specialist? I'm worried as the issues could be so spread out they would need to check everything and it would cost as much as the cars worth...

 

Regarding the question about the fuel pressure return pipes, could you elaborate on this? I don't believe the garage touched anything fuel related however my vac lines need looking at as they seem to have been changed slightly by the previous owner so something could be wrong.

 

Thanks.

Edited by Skaith4224
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