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Help with rough running

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Stephenjk
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2020/07/06 08:18:02 (permalink)

Help with rough running

Hi,
 
I went for a drive yesterday and the car started running rough it was stalling and lack of power, if I accelerated it would also stall.  it was drivable at around 2000 revs in second or third so I nursed it home.  Now it is back home and if I start it idles at 200 revs and will die if I don't have my foot on the accelerator.
 
I swapped the DME with a new one and made no difference (DME had been replaced in the last few months anyway).  I took apart the distributers and checked the secondary belt, which is fine and looks new.  I also checked the motronic error codes with scantool and that is clean, no errors.
 
I still have the old bosch coils so do you think that is the issue and if so is there a way to test for that?  I have seen a sensor issue could cause that too but hoping that would be generating an error code if that was the case.  Thoughts?
 
thanks
Stephen

13 Replies

Stig_GT3
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Re: Help with rough running 2020/07/06 08:31:39 (permalink)
Quick thought: how old is the fuel in your car?
 
It's worth keeping in mind that fuel deteriorates over time, so if your car has not been used for a few months it might need some fresh super unleaded...
 
Good luck and enjoy the driving!
Stephenjk
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Re: Help with rough running 2020/07/06 08:44:48 (permalink)
Thanks but it isnt that.  Fuel is only few weeks old, the car is my only car so i use it every week.
mcgc0
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Re: Help with rough running 2020/07/06 09:43:56 (permalink)
At least the DME relay is ruled out. Is it rough idle from cold or only once warmed up? Random or intermittent is the pain in the butt scenario - as you say, sensors, coil pack etc. You have a respectable indie you can get to for plug-in diags and readout, just to eliminate sensors or any other readings?

'90 964 C4 Velvet Red
'94 968 Sport Gaurds Red
'90 964 C4 Slate Grey
'03 Focus ST
'02 Focus ST
Alexander_Drobik
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Re: Help with rough running 2020/07/06 09:45:16 (permalink)
Hmm, could be a number of things. Coils, flywheel sensor, O2 sensor, leak around the inlet manifold. I would look around the inlet manifold and see if anything is loose, after that a trip to a specialist may be the quickest way to check on this one. Usually when the engine dies when you accelerate and/or dies on idle, it is a fuel/air issue rather than sparks - and unless it is the DME, not costly to fix. Unlikely to be a fuel pump issue but.... anyway, Good Luck.

Regards Alex
GT3 Register Secretary
Stephenjk
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Re: Help with rough running 2020/07/06 10:10:52 (permalink)
mcgc0
At least the DME relay is ruled out. Is it rough idle from cold or only once warmed up? Random or intermittent is the pain in the butt scenario - as you say, sensors, coil pack etc. You have a respectable indie you can get to for plug-in diags and readout, just to eliminate sensors or any other readings?



it first started when hot.  it would restart yesterday when hot.  This morning when the car is cold it won't even start, it picks up and splutters and dies whether I put my foot on the accelerator or not.  I'll try again later but I'm going to have to try and fix it at home, now at least so it runs enough to get to an indie.
 
mcgc0
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Re: Help with rough running 2020/07/06 12:26:34 (permalink)
When very hot (holiday traffic queues and the like) and low idling to stalling with difficult restart, one of the known issues can be the carbon canister under the left hand rear wheel arch liner. This is part of the fuel evaporative system and if the carbon canister is old or done for then it will play up with fuel induction. The canister is a consumable over the life of the car and with high milers. Not saying this is your issue but worth checking or having on the future replacement list. I paid @£80 for mine many years ago when I had woeful idling and restarting issues when hot (stuck in long traffic queue in south France). Changing the canister transformed hot idling and restarts - on the button. Good luck. Post up what you find.

'90 964 C4 Velvet Red
'94 968 Sport Gaurds Red
'90 964 C4 Slate Grey
'03 Focus ST
'02 Focus ST
mcgc0
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Re: Help with rough running 2020/07/06 12:26:34 (permalink)
When very hot (holiday traffic queues and the like) and low idling to stalling with difficult restart, one of the known issues can be the carbon canister under the left hand rear wheel arch liner. This is part of the fuel evaporative system and if the carbon canister is old or done for then it will play up with fuel induction. The canister is a consumable over the life of the car and with high milers. Not saying this is your issue but worth checking or having on the future replacement list. I paid @£80 for mine many years ago when I had woeful idling and restarting issues when hot (stuck in long traffic queue in south France). Changing the canister transformed hot idling and restarts - on the button. Good luck. Post up what you find.

'90 964 C4 Velvet Red
'94 968 Sport Gaurds Red
'90 964 C4 Slate Grey
'03 Focus ST
'02 Focus ST
Stephenjk
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Re: Help with rough running 2020/07/06 12:43:21 (permalink)
I suspect it may be a broken wire to the airflow meter.  I removed the airbox so I could get to the clip at the back of the airflow meter incase it had popped off, given the car was no longer starting it looked like something more serious.  The clip to the airflow meter was attached (and cable tied), however after doing this the car went from unable to start, to starting the first time, and on a quick drive around the block it was back to normal.
mcgc0
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Re: Help with rough running 2020/07/06 12:48:47 (permalink)
This is the problem for which there was a Technical Bulletin released for, no?  #9005.

'90 964 C4 Velvet Red
'94 968 Sport Gaurds Red
'90 964 C4 Slate Grey
'03 Focus ST
'02 Focus ST
colin129
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Re: Help with rough running 2020/07/06 13:26:30 (permalink)
Stig_GT3
Quick thought: how old is the fuel in your car?
 
It's worth keeping in mind that fuel deteriorates over time, so if your car has not been used for a few months it might need some fresh super unleaded...
 
Good luck and enjoy the driving!


 
Just as an aside, my tank is getting low, fuel light on yesterday & I was thinking that I had only filled it up a few months ago.  Turns out, I last filled up October last year.  I'm ashamed to say I have only driven 330 miles since last October 
 
Point is, the fuel has been in the tank for over 8 months and she runs like a dream and pulls like a train.  I am still going for at least a 20 mile drive every couple of weeks, hopefully off to the South of France at the end of August, fingers crossed.




Colin
964C2 Coupe 1990 Granite Grey 159K
944S2 1990 Guards Red - Gone & very sadly missed
BMW 318D - slow, slow, slow coach. Most disappointing car I have ever owned.
mcgc0
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Re: Help with rough running 2020/07/06 13:30:08 (permalink)
colin129
... hopefully off to the South of France at the end of August, fingers crossed.



Perfect - makes up for the loss of the Le Mans trip mid-June.. :)

'90 964 C4 Velvet Red
'94 968 Sport Gaurds Red
'90 964 C4 Slate Grey
'03 Focus ST
'02 Focus ST
Stephenjk
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Stephenjk PCGB Member
Re: Help with rough running 2020/07/06 13:47:10 (permalink)
mcgc0
This is the problem for which there was a Technical Bulletin released for, no?  #9005.



yes this one.
https://rennlist.com/forums/964-forum/264897-technical-bulletin-t1-90-maf-wiring-harness-mod.html
 
i have that mod, though i haven't taken apart the clip to check exactly how it was done.  I can see the wires are not coming straight out as they were pre mod.  Instead they are coming out wrapped around the clip so they stay very close to the MAF.  The clip has a cable tie around it so i did wonder whether it was a proper job.  Anyway I doubt the heating is interfering but it could be the mod has fatigued the wires.
colin129
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Re: Help with rough running 2020/07/07 16:22:11 (permalink)
mcgc0
colin129
... hopefully off to the South of France at the end of August, fingers crossed.



Perfect - makes up for the loss of the Le Mans trip mid-June.. :)




tbh, we had always planned to miss the Toyota show, looking forward to the changes for next year though.

Colin
964C2 Coupe 1990 Granite Grey 159K
944S2 1990 Guards Red - Gone & very sadly missed
BMW 318D - slow, slow, slow coach. Most disappointing car I have ever owned.
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