Hi,

The Sapphire is having a bit of trouble running right. She idles far too high from start up and it doesnt cure itself even after driving.

So I assumed it was the ISCV, swapped a spare one over and the problem still didnt stop. So I unplugged the ISCV and she idles much more nicely.

Then I plugged it back in and unplugged the TPS, that brought the idle to a much nicer level as well. and its the same with both unplugged.

Any ideas as to what the issue is??

 

Have you checked if the throttle body housing is dirty and the throttle not closing fully?

Could be TPS, find which is signal wire and test it with meter, should be around 0v with closed throttle, smoothly going up to 4-5v on full throttle.

Maybe some adjustment on the TPS, not sure,as I haven't worked on one of those for many years!

Is there any adjustment on the throttle for base idle?

 

Good info on this link - ftp://ftp.capri.pl/user/trojkat/elek...corpio_2.9.pdf

Sensor tests etc...

 

Cheers for that.

I'll have a go at testing the TPS first because it seems like the most likely cause.

Theres no adjustment on the TPS but looking at that link you sent the base idle can be adjusted.. I just dont think I should do that just yet because the base idle is completely fine with the sensor disconnected.

 

If the engine continued to run with the ISCV un-plugged, then I would suspect an air leak on the inlet system somewhere.

The RS2000 16v has a similar setup, and an air leak on the inlet system cause's the engine to run on after the ISCV is un-plugged, and idles high with it plugged in.

A quick test is to spray some WD40 around the inlet system with the engine running, any change in the engine note as you spray, highlights a potential leak spot. Don't forget the area around the fuel rail to inlet manifold seal, at each injector, as these round thick washers have a habit of leaking over time.

 

Tried doing that air leak test earlier on today. Didn't have any effect on it whatsoever. however when i loosened off the ISCV the RPM picked up.

Then I was having a look around and spotted this



it was connected to a wire running to the ISCV by bullet connectors. I removed it and connected the two bullets together and the car now runs perfectly with all sensors in place.

I tested the above item and its a Diode and a resistor.. Any idea what its for? and is it something that shouldnt be removed?!

 

morning bump

 

Not sure how to identify the difference but some of the ISCVs have the diode built in and others dont. It may be that your ISCV was originally one without the diode so there was one fitted to the wiring. If the ISCV has been replaced with an integral diode type, this may cause an issue and run better with the external one removed.

 

What he said ^^, some valves have a built in diode and other's don't.

However as the diode just allows current to flow in one direction only I can't imagine it causing a problem as that direction won't be changing.

Never heard of resistors for them, it certainly looks aftermarket, as I can't imagine that being OE.

Martin

 

Thanks for the replies guys.

Had a look through a loom i have for an XR4x4 2.9, they use the same ISCV and theres no sign of the diode.

Been using the car without the diode in place and it behaves perfectly, except for struggling to stay running or idle correctly from cold. once its been driven for a minute or two its fine then.

Getting veeerry confused.

 

If the issue is now only from cold then I would suspect the coolant temperature sensor. It's on the inlet manifold behind the stat housing, larger of the two sensors with the multiplug on it. This signals the coolant temperature to the ECU. When cold, the idle speed is increased via the ISCV and the injector pulse is lengthened to enrich the mixture. If the sensor thinks the engine is already hot then it won't trigger this cold start sequence.

 

Did you check the crankcase vent (esp. the small hose)? False air let the idle go crazy if this hose cracked. It's a bit hidden by the exhaust manifold.

Do you hear hissing sounds in the exhaust manifold region?

 

Or even remove the ISCV and try cleaning, as they are renown for clogging up with carbon which causes problems, even if it does not solve your problem, it's likely to prevent a problem in the future.

Martin

 

Ok cleaned out the ISCV again today and no change in the situation.

Then went and checked the crankcase vent and all pipes are perfect, no cracks or leaks.

Anybody know how to check the coolant temperature sensor to see if its working as it should?

 

If in doubt, just swap it out

There is no way of testing, unless you have a temperature vs resistance scale and can test it across this temperature range.

Sure you can measure the output but it's never going to be an accurate test!

Martin

 

Ok boys and girls... Think I've this one put to bed now.. I'd gotten a replacement TPS and tried that. Didnt make a drop of difference.

So got thinking, pulled the air temp sensor out of the inlet manifold, thing turned out to be covered in black crap, cleaned it off with some carb cleaner and put it back in. started the car and still not running right.

chanced my arm and put the diode back in that line, started first time, idle dropped down to a nice level. seems to be perfect now except still a tiny bit rich but hopefully a drive will sort that out.

Cheers for all the help people!