Cowboi

my engine wont idle. and it just dont seam right when reving it. it sticks an higher revs and is just generally not going to well.

i tested the tps. its got a 5v supply. and has 0v when closed and 4.9v when open. there is nothing in between. i mean it dosent go slowly betweehn 0 and 5 volts as you open the throttle. is this right?


ive taken the iscv off and started the car when it was totally disconnected. it actually ran better withg out it there at all. it tried to idle, was very low and lumpy like at about 500 rpm or so. but it was at least trying.
i gave it a bit of a clean up and re fitted it. it hasnt solved anything and its still not idleing at all.

is there anything i can do to test it. or can anyone reccomend any things to try?

cheers

btw its a vauxhall 2ltr 16v (c20xe) i know its not a ford but surely the bits im looking at cant differ much between most cars.

Cowboi

any one got any ideas?

ive gotta pop out soon so wont be at the car much longer

scruffythefirst

Common problem on the 2lt 16v vx lump mate. bassically the ISCV gets gummed up with crap from the breather. There is a documented fix for it, have a look on migweb. You need to clean the valve and solenoid and fit a valve from vx in the breather pipework and clean the entire inlet tract. Got to do mine soon, but as I can heal and toe it doesnt have to idle so it can wait a bit longer

Petrucci

i had the same problem on my Escort a few years ago, and it turned out to be a very badly set idle speed, which caused the ISCV to do stupid things to compensate, and result was bad idling, stalling, and a kind of "sticky" area around 2500 rpm, where the car stayed for 1 or 2 seconds before decreasing revs to idle again (great when you want to stop quickly LOL )

Cowboi

thats just what its doing. takes a long time to drop in revs, and when it does it just cuts out.

it used to be fine! but i didnt have all the water pipes. when i got them and filled it up. i went to give it a good run and this happened.

i'll try giving it all a really good clean. and see what happens.

but it does sound like its the iscv at fault

Petrucci

well i also thought mine was faulty, even bought a new one after trying to clean mine, and of course new one made no difference at all
I suggest you try and set up again your base idle speed to see if it helps, as it was my only problem... AFAIK, it has to be set with the ISCV unplugged, and you know your idle speed is correct when plugging or unplugging the ISCV with engine turned on makes no difference at all in revs.

scruffythefirst

The crank sensor is also known for being rubbish on these, although if the idle valve is stuck open or only moving partially then that can give the symptoms you describe.

Cowboi

ive taken the iscv off and connected it to a battery. the shutter was only opening slightly, after some lashing of wd40 and some brake fluid i managed to get it opening fully. i put it back on the car but it hadnt changed anything.

i sprayed some wd40 own the pipe that goes between the sfi box and the iscv. gave it a few minutes to soak through and then started it. it didnt fix it but after a while of keeping it running by reving it it actually managed to idle for a while on its own. very lumpy, dropping to low revs and just about picking itself back up to just over 1k. but it didnt manage that for long. not sure if thats cos it ran for a while of coz of the cleaning of the iscv.

i tried un plugging the isv and that didnt effect anything.

then as i was getting rather annoyed i decided to try un plugging the air flow sensor just before the sfi box. this made the enging idle at about 2-2.5k after a while that rose to 3k and thats where it sat. seams liked it would of stayed there all day more than happily.

does this mean anything? ie could it be the air flow sensor?

do u think i should take the iscv back off and soak it for a while just to make sure its totally clean and free flowing?


like i said it used to run fine and idle perfect.


when i keep it running by revving it, it does pop and bang a bit. do you think it could be out of timing?

Jim Galbally

what does it idle like with ISCV unplugged? you need to set the base idle (ie unplug ISCV set it mechanically) so that the engine idles perfectly when warm (normally about 900rpm) THEN you plug in the ISCV. the iscv is only used to keep the revs up on cold starts etc. etc. it shouldnt be needed when idling normally.

also the TPS should go from 0-5v smoothly yours sounds donald ducked (or wired in WRONG) its likely not helping!!!

Jim Galbally

oh and shit timing can cause silly buggers with the idle (shit fueling can too)

Jim Galbally

hold on just had another think... the track in your TPS could be broken. it doesnt make a contact until it hits the very end of the track then you get a signal. Can you nick a TPS off of another car to try?

Cowboi

im starting to think now that ity could be the tps.

i thought it was strange how it had 0v all the way untill the throttle was fully open when it had 5v on it.

might see if i can get hold of one some where to test it with.

Cowboi

it dosnt effect anything when its unplugged. still as bad

the iscv was defo a bit dodgy though. it wasnt opening the whole way. given it a clean up now and it seams to be working better.

i'll keep trying. hopefully i'll find the problem soon.

Jim Galbally

sounds less like a faulty ISCV to me. if the valve's closed then it aint raising the idle, so another management fault somewhere by the sounds of things (TPS is the likely culprit)

Cowboi

cheers jimbo
i'll c if i can get hold of a spare tps and c wot happens

Matt

yep it indeed should move slowly through the voltage range

mine bust and the fuelling went haywire so car drove like shit on anything other than WOT where it fuelled as it should

Cowboi

looks like the tps needs changing any way. if its at fault for the idle or not seams like it needs doing.

foreigneRS

i thought the tps is not so much a tp sensor on those as a tp switch?

Cowboi

ive just been told the same thing mate!

now i just dont know what to do! it seams the tps isnt playing up after all. as far as i know the iscv is now working and not so sure it would cause this much problems anyway.

maybe the its air flow sensor.

i wish i had a mate with the same engine so i could swop some bits and see what happens

Jim Galbally

foreign, its an EFI redtop not an MFI RS Turbo they should use proper 0-5v TPSes

Cowboi

apparently not jim, the new ones do. but the old red tops dont.

gotta double check that but it was from a reliable source!

Cowboi

thought i bring this back to the top as im going back to the car tomorrow and was just wondering what sort of things i should look at first to get an idea of what could be the problem.

cheers