What do you think is wrong?
Discussion
Hi Guys,
Had my 94 Chim for a couple of months. Last 4 weeks or so done some long journeys (400+ miles) and developed revving problem after 20 mins or so of driving.
It's like the classic idle revving problem - struggles and will often stall at lights. But it also kangaroos at low revs in all gears. When it does this, I can hear the fuel pump hum dip in pitch like it's struggling. The oil pressure will also dip slightly at the same time.
Clean the stepper, yep.
It only does it when warm, and by warm, I mean after 20 mins of driving or so. A nice stretch of fast road will bring the temp gauge down to 70-75, but this doesn't stop the problem once it's started.
Got really bad last week, had continuous stalls on the way to work and so took it to a Fuel Injection specialist. He replaced some leads and sensors and charged 200 quid.
Thought it had fixed the problem, as it's been fine driving through hideous Nottingham rush-hour traffic for a whole week.
Whilst it now runs like a rocket, I had the same old problem driving to Manchester today, would not idle once I reached the traffic after fast empty roads. And most of the way back, it would kangaroo if I let the revs drop to 2000 or below in any gear. Above 2000, its fine. Better than fine. Quicker than it's ever been.
Then, 2/3 of the way back, the kangarooing suddenly dissapppeared, along with the low-revving problems and the car returned to normal without warning.
I know I've gone on a bit here, but does anyone have any ideas what these symptoms, and their timing might mean is still wrong?
I'm running continuous tanks of Optimax never letting it fall below half way. Occasionally, also when warm, the oil pressure dial will max out suddenly, like its shorting. But it doesn't seem to corelate to the other problems.
Many, many thanks for your time
Mark.
Had my 94 Chim for a couple of months. Last 4 weeks or so done some long journeys (400+ miles) and developed revving problem after 20 mins or so of driving.
It's like the classic idle revving problem - struggles and will often stall at lights. But it also kangaroos at low revs in all gears. When it does this, I can hear the fuel pump hum dip in pitch like it's struggling. The oil pressure will also dip slightly at the same time.
Clean the stepper, yep.
It only does it when warm, and by warm, I mean after 20 mins of driving or so. A nice stretch of fast road will bring the temp gauge down to 70-75, but this doesn't stop the problem once it's started.
Got really bad last week, had continuous stalls on the way to work and so took it to a Fuel Injection specialist. He replaced some leads and sensors and charged 200 quid.
Thought it had fixed the problem, as it's been fine driving through hideous Nottingham rush-hour traffic for a whole week.
Whilst it now runs like a rocket, I had the same old problem driving to Manchester today, would not idle once I reached the traffic after fast empty roads. And most of the way back, it would kangaroo if I let the revs drop to 2000 or below in any gear. Above 2000, its fine. Better than fine. Quicker than it's ever been.
Then, 2/3 of the way back, the kangarooing suddenly dissapppeared, along with the low-revving problems and the car returned to normal without warning.
I know I've gone on a bit here, but does anyone have any ideas what these symptoms, and their timing might mean is still wrong?
I'm running continuous tanks of Optimax never letting it fall below half way. Occasionally, also when warm, the oil pressure dial will max out suddenly, like its shorting. But it doesn't seem to corelate to the other problems.
Many, many thanks for your time
Mark.
Mark. It could be any number of things and starting with the stepper motor, as you know, is a good place to begin. Two other sensors that could cause such a noticeable problem are the throttle potentiometer, which tends to be worst at very light throttle openings if it is faulty, and the coolant temperature sensor (which can make the fuel ECU think the car is cold.
Steve Heath's bible shows tests for these and other components, if you have a multimeter. If you don't, you should be able to pick one up for £20 or so.
Steve Heath's bible shows tests for these and other components, if you have a multimeter. If you don't, you should be able to pick one up for £20 or so.
Could be anything,
First check fuel cap, make sure it is venting and not causing a seal, after car starts playing up stop and check you don't get a rush of air when removing fuel cap, if so try a new one.
Next, new plugs, heat shields, rotor arm, dizzy cap, rotor arm, leads (but said leads already done) and coil from ACT-Products.
Keep spares just in case, maybe good.
Fuel & Air filter, when last done?
Have a trawl through PH and hire out the ECU fault reader for £10/WEEK. See the bible for codes.
After that make a list of work carried out and take it to a V8 Specialist if faults still exist.
Hope you get to the bottom of it.
Paul.
First check fuel cap, make sure it is venting and not causing a seal, after car starts playing up stop and check you don't get a rush of air when removing fuel cap, if so try a new one.
Next, new plugs, heat shields, rotor arm, dizzy cap, rotor arm, leads (but said leads already done) and coil from ACT-Products.
Keep spares just in case, maybe good.
Fuel & Air filter, when last done?
Have a trawl through PH and hire out the ECU fault reader for £10/WEEK. See the bible for codes.
After that make a list of work carried out and take it to a V8 Specialist if faults still exist.
Hope you get to the bottom of it.
Paul.
The classic 'only gives problems when hot' fault is a failing ignition coil. Do you still have the original Lucas coil fitted?
If yes, check the coil very carefully for signs of a dark brown oil residue, particularly weeping from the HT lead socket. The Lucas coils fail under temperature and give all sorts of running problems. One minute the car goes like a rocket the next minute it pulls badly with no real zip at all.
The cure is to replace the Lucas coil with an identical unit made by Bosch which costs around £50(see bible for details on part number of coil)
If yes, check the coil very carefully for signs of a dark brown oil residue, particularly weeping from the HT lead socket. The Lucas coils fail under temperature and give all sorts of running problems. One minute the car goes like a rocket the next minute it pulls badly with no real zip at all.
The cure is to replace the Lucas coil with an identical unit made by Bosch which costs around £50(see bible for details on part number of coil)
Hi Mark,
You're welcome to try this; www.pistonheads.com/sales/48467.htm
I always email a list of fault codes when the reader is posted. Plus I'm happy to help with fault finding and advice on using the reader.
You're welcome to try this; www.pistonheads.com/sales/48467.htm
I always email a list of fault codes when the reader is posted. Plus I'm happy to help with fault finding and advice on using the reader.
Thanks Richard, I may take you up on that offer.
Just reading an old post about a fuel pump not working (at all).
Someone suggested to check the relay and asked if it was hot.
I had my ECU out earlier and had a quick feel around the cables and relays and noticed that the metal-cased relays were very hot.
Is this normal? If not, could this be my problem, a faulty fuel-pump relay?
What makes me think it might be is the dip in pitch of the pump's hum when the revs dip. I just don't know if the labouring revs are causing the pitch dip, or the other way around.
Just reading an old post about a fuel pump not working (at all).
Someone suggested to check the relay and asked if it was hot.
I had my ECU out earlier and had a quick feel around the cables and relays and noticed that the metal-cased relays were very hot.
Is this normal? If not, could this be my problem, a faulty fuel-pump relay?
What makes me think it might be is the dip in pitch of the pump's hum when the revs dip. I just don't know if the labouring revs are causing the pitch dip, or the other way around.
Mark476 said:
Hi Guys,
I can hear the fuel pump hum dip in pitch like it's struggling. The oil pressure will also dip slightly at the same time.
Mark.
I am curious about this, I agree with all the above and a dodgy pump relay could certainly be implicated. You also mention the oil pressure dipping, now the obvious explanation is that this will occur as the revs drop, but the other is - could this be a general electical system system fault, in particular a poor earth, say from the battery, which could then cause an intermittent drop in system voltage and cause your symptoms. Is there any other evidence of dipping voltage , for instance do the lights dim when the car hesitates?
Mark476 said:
It's kicking out some serious smoke as it struggles too. Boot lid is caked in soot.
That sounds like intermittent over fuelling, possibilities that spring to mind include:
Air flow meter problem.
Fuel pressure problem (sticking regulator causing excessive pressure in the fuel rail -
might also explain the pump labouring....) ECU problem (making sure you rule out minor stuff like poor / dirty connection at the multiplug, wiring fault - broken loom)
Injector problem (sticking open, but that would tend to cause a regular misfire rather than general power loss).
Lambda sensor malfunction / out of range (might help to borrow / hire a fault code reader for the ECU)
Something else.....?
Result.
Those nice chaps at TMS had a look for me, and apparently my stepper motor was missing a section of the housing!?!
I'd had a go at cleaning it the other week, and not noticed anything amiss from the procedure described in the good book. But I guess they know what they're doing over and above what I am slowly picking up.
Anyways so this was obviously causing an airleak, and they also setup my throttle again.
Running great again, been in lots of traffic, engine hot, no problems, like a rocket again.
thanks for all your help
Mark.
Those nice chaps at TMS had a look for me, and apparently my stepper motor was missing a section of the housing!?!
I'd had a go at cleaning it the other week, and not noticed anything amiss from the procedure described in the good book. But I guess they know what they're doing over and above what I am slowly picking up.
Anyways so this was obviously causing an airleak, and they also setup my throttle again.
Running great again, been in lots of traffic, engine hot, no problems, like a rocket again.
thanks for all your help
Mark.
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