Chim runs like crap since fuel hoses changed
Discussion
As the fuel hoses on my Chim were starting to show signs of perishing I've just replaced them – but the car is now running like crap.
When I first got it back together and started again, the revs were initially all over the place until things settled down, which considering the battery had been disconnected and the fuel had to fully charge wasn't too much of a surprise.
What was a surprise was a whistling sound (rather like an old kettle boiling) that happened every so often. I did wonder if it might be an air leak, but a check shows everything connected, and there's no splits in any of the hoses.
Took it for first run yesterday, and it no longer runs or pulls smoothly at low revs and runs roughly when revved hard through the gears. And it still whistled on and off whenever the mood took it.
Seemed to run quite smoothly on motorway, and pulled OK from 70 to 80 in 5th – though whistled as it accelerated.
Back off the motorway it was shunting badly at around 2500 rpm, the idle speed was low and it once died completely when stopping in traffic (though fired up again).
Fired it up earlier today, and revs go between 2500 and about 500 several times before settling down, and it still whistles on and off.
In order to change the fuel lines I had the plenum off, so while I was at it I decided to clean the stepper valve. Turned out not to be very dirty, but I gave it a blast of carb cleaner and a wipe, after which it was nice and clean.
Is it possible I've somehow damaged the stepper valve when cleaning it? Because I can't think of anything else I've done that could have upset the way the car runs.
Any ideas/suggestions welcomed.
When I first got it back together and started again, the revs were initially all over the place until things settled down, which considering the battery had been disconnected and the fuel had to fully charge wasn't too much of a surprise.
What was a surprise was a whistling sound (rather like an old kettle boiling) that happened every so often. I did wonder if it might be an air leak, but a check shows everything connected, and there's no splits in any of the hoses.
Took it for first run yesterday, and it no longer runs or pulls smoothly at low revs and runs roughly when revved hard through the gears. And it still whistled on and off whenever the mood took it.
Seemed to run quite smoothly on motorway, and pulled OK from 70 to 80 in 5th – though whistled as it accelerated.
Back off the motorway it was shunting badly at around 2500 rpm, the idle speed was low and it once died completely when stopping in traffic (though fired up again).
Fired it up earlier today, and revs go between 2500 and about 500 several times before settling down, and it still whistles on and off.
In order to change the fuel lines I had the plenum off, so while I was at it I decided to clean the stepper valve. Turned out not to be very dirty, but I gave it a blast of carb cleaner and a wipe, after which it was nice and clean.
Is it possible I've somehow damaged the stepper valve when cleaning it? Because I can't think of anything else I've done that could have upset the way the car runs.
Any ideas/suggestions welcomed.
I once had a howling type noise at idle that drove me nuts until I put my ear down by the air filter and heard it coming through the intake.
Must have been a point where the stepper was open enough to cause it but I never got round to finding it as it just stopped.
Just double check the seal on stepper to plenum.
Must have been a point where the stepper was open enough to cause it but I never got round to finding it as it just stopped.
Just double check the seal on stepper to plenum.
Thanks for the replies chaps.
Took the plennum off to check hoses etc when got the car running again and the problem showed up. Put it back with generous bead of sealer, so can't see it leaking there.
Had all induction apart 3 years ago when I fitted ACT superflare kit and didn't have these problems. Only difference is that this time I removed stepper motor, which is why I'm wondering if that's where the problem lies.
Put good bead of lock and seal around stepper threads, so should have seal there.
Took the plennum off to check hoses etc when got the car running again and the problem showed up. Put it back with generous bead of sealer, so can't see it leaking there.
Had all induction apart 3 years ago when I fitted ACT superflare kit and didn't have these problems. Only difference is that this time I removed stepper motor, which is why I'm wondering if that's where the problem lies.
Put good bead of lock and seal around stepper threads, so should have seal there.
Edited by grahambell on Tuesday 6th June 10:50
It should really have a composite gasket if I remember correctly and I often used a bit of plumbers tape around the stepper motor threads for good measure.
You haven’t knocked the temp sensor wire on the inlet manifold have you.
At this point I’d use Rovergauge to check what’s going on with both stepper and temp sensors etc etc.
You haven’t knocked the temp sensor wire on the inlet manifold have you.
At this point I’d use Rovergauge to check what’s going on with both stepper and temp sensors etc etc.
Edited by Classic Chim on Tuesday 6th June 13:37
Induction pipes all ACT smooth bore stuff and only 3 years old. Seem OK.
Temperature gauge wiring seems to be on OK and gauge was working fine when driving.
Yes, stepper motor should - and indeed did have - composite gasket, though I've now removed it as I've taken stepper motor back off to give housing a good go with carb cleaner and compressed air just in case a bit of muck was blocking something.
Does anyone know if stepper motor should activate with ignition? After taking it out I fitted it to plug and switched on ignition, but nothing seemed to happen.
Don't have Rovergauge so unfortunately can't check anything there, but thanks for the suggestion.
Temperature gauge wiring seems to be on OK and gauge was working fine when driving.
Yes, stepper motor should - and indeed did have - composite gasket, though I've now removed it as I've taken stepper motor back off to give housing a good go with carb cleaner and compressed air just in case a bit of muck was blocking something.
Does anyone know if stepper motor should activate with ignition? After taking it out I fitted it to plug and switched on ignition, but nothing seemed to happen.
Don't have Rovergauge so unfortunately can't check anything there, but thanks for the suggestion.
Turn the ignition on without starting it and turning off again, you should hear the stepper motor being wound back in. You get multiple clicks because it is all the way back.
It does this every time you switch off to give it a datum to start from, because the ECU receives no feedback as to how far the plunger has been actually moved when the engine is running, so is unaware if it is not responding correctly to signals to move.
It does this every time you switch off to give it a datum to start from, because the ECU receives no feedback as to how far the plunger has been actually moved when the engine is running, so is unaware if it is not responding correctly to signals to move.
Thanks for that info. Had the ignition turned until dash light came on but stepper did nothing - and I turned the key through the open door so that I could stand by the car and observe the stepper as I did it.
So it's increasingly looking like a fault with the stepper or else the feed to it.
So it's increasingly looking like a fault with the stepper or else the feed to it.
It's only on turning ignition OFF that you'll only hear it motor back. With the window open or leaning in an open door, you will definitely hear it.
Every time the engine is turned off, the ECU sends more than enough pulses to motor the shaft back all the way back in. The clicking you hear is the motor running out of free movement.
It starts from this position and then motors out as demanded by the ECU to adjust the bleed air flow and therefore, idle speed.
Every time the engine is turned off, the ECU sends more than enough pulses to motor the shaft back all the way back in. The clicking you hear is the motor running out of free movement.
It starts from this position and then motors out as demanded by the ECU to adjust the bleed air flow and therefore, idle speed.
Well, I fitted the new stepper motor and still not running right - but it is running differently.
Pretty much dies on start up unless you blip the throttle, then revs go up and down several times until it settles to reasonable idle speed. And it now only seems to do the boiling kettle impression between 1000 and 1100 rpm.
After checking that I was actually getting power to the stepper motor plug (yes, but only with engine running) I decided to plug in the original stepper. Start the engine, and the plunger comes out, stop the engine and it goes back in. So as that seemed to be working OK I refitted it - but it made no difference.
Car seems to run OK at 70mph, but is now flat with no real pick up if you put your foot down in top. Also still runs rough under hard acceleration, almost like it's not running on all 8. And it still doesn't like running at low revs, whereas it used to be OK at 30mph in 5th before I changed the hoses.
Fuel lines are definitely connect right way round.
Before fitting the new stepper, I disconnected the battery, which I believe restores the ECU to default settings?
Have tried smoke test with smoke matches, and no sign of air being drawn in, so doesn't look like air leak.
And to add to the fun, my instrument illumination has now failed. FFS!
Pretty much dies on start up unless you blip the throttle, then revs go up and down several times until it settles to reasonable idle speed. And it now only seems to do the boiling kettle impression between 1000 and 1100 rpm.
After checking that I was actually getting power to the stepper motor plug (yes, but only with engine running) I decided to plug in the original stepper. Start the engine, and the plunger comes out, stop the engine and it goes back in. So as that seemed to be working OK I refitted it - but it made no difference.
Car seems to run OK at 70mph, but is now flat with no real pick up if you put your foot down in top. Also still runs rough under hard acceleration, almost like it's not running on all 8. And it still doesn't like running at low revs, whereas it used to be OK at 30mph in 5th before I changed the hoses.
Fuel lines are definitely connect right way round.
Before fitting the new stepper, I disconnected the battery, which I believe restores the ECU to default settings?
Have tried smoke test with smoke matches, and no sign of air being drawn in, so doesn't look like air leak.
And to add to the fun, my instrument illumination has now failed. FFS!
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