Idle problems.

[hts]

Got some strange issues with my puma converted zetec-s and wondering if any of you have any idea on whats wrong with it.

So far I've tried replacing the ICV, TB and TPS, MAF, twice each (One from a working car and 2nd they were new). Also couldn't find any air leaks.

PAS Pressure switch is unplugged as I've removed the PAS pump etc.
Inlet is a LMS item but had tried using the standard inlet to no avail.

Unfortunately because the car is off-road and not insured/taxed I can't take it to see if any fault codes are present on the ECU (TAPE).

1. When started the car will idle at 3-4k.

2. Press the clutch down, revs drop to about 1.5k and you can rev the car as normal etc until the clutch is back up and its shoots back to 3-4k.

3. Unplug the MAF, car idles mostly ok (Little unsteady on the revs - fluctuates by about 50-100rpm) and revs will hang if you use the accelerator (Back to 3-4k) until the clutch is down.

From what I've read the clutch being depressed and the car idling more normal is the opposite to the problem most encounter.

If anyone has any ideas or suggestions they will be most appreciated.

If any more info is needed please ask and I'll update anything else if i remember anything else and will try and get a few videos at the weekend if it would help.

Regards,
Dan.

 

[Van_Dammesque]

I am no expert but have a look at this thread and see if you have not tried the suggestions there.

 

[Anonymous]

How long have you have this Idle issue..? Straight from the off on this 'build/conversion'?

PAS Pressure switch is unplugged as I've removed the PAS pump etc.

This... COULD be your issue.

When the steering is on full load, the pressure switch goes to open. This cuts the signal to the ECU which forces the revs up to compensate for the extra load the steering system is putting on the engine.
When the steering reverts back to normal/low load, the pressure switch closes and returns a signal back to the ECU which drops the revs back down again.

Unplugging the pressure switch has the same effect as having the steering on full load... the ECU thinks the steering system is loaded up and forces the revs up to compensate.

As an idea, try bridging the contacts in the plug with a piece of wire.....

If it don't work, I've typed all this for nothing!!

 

[hts]

How long have you have this Idle issue..? Straight from the off on this 'build/conversion'?

Yes, since its been converted. Although, I did buy the project half completed but had since re-done almost the whole lot anyway.

Thanks for the quick replies, I'll try the PAS plug at the weekend and post back here with the results.

Regards,
Dan

 

[oilburner]

The engines throwing a wobbler because someone stuck it in a Fiesta!!! ;-)

 

[hotrodspike]

I had the same problem once, the auxialary belt driving the PAS snapped and the revs shot up to 3-4K and wouldn't drop. Obviously because the sensor was trying to stop the engine from stalling (sensor switch open) the ECU was keeping the revs up. Because you've took off the PAS could be part of your trouble, especially as you've disconnected the switch on the pipework. What you need to do is somehow tell the ECU that the car doesn't have PAS and not just physically removing the components without removing the ECU program (if that's doable).

 

[tintin]

How long have you have this Idle issue..? Straight from the off on this 'build/conversion'?

PAS Pressure switch is unplugged as I've removed the PAS pump etc.

Unplugging the pressure switch has the same effect as having the steering on full load... the ECU thinks the steering system is loaded up and forces the revs up to compensate.

As an idea, try bridging the contacts in the plug with a piece of wire.....

This is what you need to do for sure.

 

[hts]

Haven't had a chance to do anything on the car yet, will update this thread tomorrow!

 

[hts]

Update:

I've bridged the pas pressure switch plug as suggested (Actually cut the plug off and connected the wires together), and it made a very slight difference in that the idle is now stable and doesnt fluctuate by 50-100rpm.

As I had purchased a hand held code reader i plugged it in today and used the 'Live data' option (Pretty cool tbh) and without even turning the engine on the TPS is reading 20-ish% throttle!? - Even though I've tried 2 before now already but meh...

Although unplugging the TPS didn't help much and the car still idled at 2k ish

Will update more tomorrow when I have another look at the car and hopefully without a massive migraine.

 

[evilrob]

On my Scanguage, the TPS default value (i.e. what you would expect to be zero, with foot off pedal) is returned as 16 for some reason, but progresses smoothly up through 17, 18, 19 etc. as you press the noisy pedal.

 

[hts]

Thanks Rob, guess its not necessarily that then :-(

 

[Anonymous]

When you offer the TPS up to the side of the throttle body, it wont be lined up as it should. You have to turn it to line it up with the bolt holes so you are already turning the TPS to get it bolted up. This is probably where the 'non zero' reading comes from.

 

[Ginger Tom]

Throttle position sensors shouldn't be set at 0 for closed throttle and 100 for WOT as this fucks them

 

[hts]

Throttle position sensors shouldn't be set at 0 for closed throttle and 100 for WOT as this f__ks them

Cheers, also explained why it toped out at 95ish% at WOT

 

[hts]

Just to update this thread: Problem has since been fixed.

Borrowed a friends ECU; picked up an issue with the cam timing, took the rocker cover off etc; cam timing on the inlet was massively out (Upon closer inspection whoever had timed the engine previously didn't do either of the bolts that go through the pulley into the camshaft up tight enough as i literally could undo it by hand).

Re-timed properly and while I was at it installed some LM3 cams problem solved!

So thank you to everyone that contributed and tried to help!