VW_chris 10 Posted December 1, 2015 right then where to start.... The problem the car idles rough/hunts (different every time you start/kill the engine) from 650, 900, 1000, 1100. it runs rough, it feels like its holding back (not as powerful as usual) its occasionally difficult to start, 2/3 attempts and 5/10 times pulling away from lights, it seems like missfires in 1st and 2nd but isnt a missfire? if that makes sense, as in the engines holding back for whatever reason. (may be a seperate issue, but the fuel pump relay clicks constantly on ignition :scratch: ????) whats been done 92 12v very early vr6 (original engine, slight mods) had the car scanned today, knowing the crank sensor comes up every time you scan a car regardless if its at fault or not, it was disregarded. it threw theese codes. 00533 - idle speed regulation - adaptation not set. 00537 - lambda sensor - limit exceeded. that would suggest an air leak. but there isnt one, all hoses have been checked, and double checked whilst running with brake cleaner. the front engine knock sensor (just behind the oil cooler) was knackered. causing the above problem to get worse, replaced with gen part, further issues disapread, leaving the original issues. ive replaced the HT leads, coilpack (single point version), cleaned out the dizzy/rotor arm, new spark plugs, main engine harness conector is ok, no corrosion inside, ECU has been out twice, stripped it down, no signs of tracing or any water damage. i read on vortex, a guy had a similar issue with regards to the fuel pump relay clicking, upon removing the ECU whilst leaving it connected, thus isolating it from ground, the fuel pump relay stopped clicking, i tried this out, whilst measuring what voltage was passing from the ECU to ground which was 0.32v. (to me, that instantly sparked, internal short. now, the ECU is meant to be earthed, other wise it would be isolated from factory. so the issue must be elsewhere, but why stopping that 0.32v earthing stopped the fuel pump relay clicking, i dont know) Electric testing..... query on the ISV harness, for those who may know, what is the supply voltage meant to be to that unit? im currently getting 0.86v at the unit on idle. from what ive read, the unit doesn't receive higher voltages until higher rpms??? also the unit does not make a noise, no buzzing on ignition, is that right?? Any feedback is greatly appreciated, any possible ohm ranges for resistance testing one the 12v VR6 ISV unit would also be great. god i love these cars..... Quote Share this post Link to post Share on other sites
swiftkid 1 Posted December 1, 2015 Guarantee its MAF, its always MAF. Get it up to temp, unplug it, if engine splutters its fine, if it doesn't do anything its not working and would explain a lot of the symptoms above. When MAF goes it always throws up a lambda fault. Quote Share this post Link to post Share on other sites
Jim Bowen 1 Posted December 1, 2015 Mine was having an idle issue and a similar fault code, didn't throw up the lambda one though. Thought i'd ruled out the isv by cleaning it and then swapping it for a used one. Ending up fitting one of these ISV's and it sorted the issue straight away, plus a lot cheaper than most ISV's http://www.ebay.co.uk/itm/151518276348 am not saying thats your problem, but its a cheap way to rule the ISV out. Quote Share this post Link to post Share on other sites
Mccorrymark 10 Posted December 1, 2015 Mine has a similar issue turned out the fuse box wiring was knackered fecking the whole thing up I tried everything before I found that fault was near about to replace the dizzy :0 Quote Share this post Link to post Share on other sites
VW_chris 10 Posted December 1, 2015 yeah i had a not starting issue about a year ago and replaced the dizzy then, funnily enough it didnt fix it.... ill try disconecting the MAF when its hot shortly, im about to go out and do an oil change on it before i go to work..... so ill check that, as for the ISV, im tempted to replace the part but would sooner buy an OK/used part than something that cheap off ebay, but i think its one to buy.... youd think it would just be happy. ive just bought cams for it..... Quote Share this post Link to post Share on other sites
VW_chris 10 Posted December 1, 2015 right, been out for the last hour working on it, gave it an oil change, wouldnt make a difference but i do it every 3 months, so its done. warmed it up, disconected the maf, it noticed it but didnt do anything, didnt stutter ect.... along with the ISV not making a noise when ignition is on, asuming its meant to, ill have to see if i can get a MAF and ISV asap..... whats best for a MAF assuming mines no good? used genuine parts or topran euro car parts crack? Quote Share this post Link to post Share on other sites
swiftkid 1 Posted December 1, 2015 Try giving the maf a clean with electrical cleaner, presume yours is the early horrendously expensive one so a clean might be first port of call before you start spending cash. You could also try taking the car for a spin with maf unplugged and see if it makes a difference Quote Share this post Link to post Share on other sites
VW_chris 10 Posted December 2, 2015 im going to try a few things over the next week, i always get to the source of a problem, regardless of what it costs, aha.... ordered a primary stage for the coilpack, rather than just swapping it out for what i think are good coils, im putting in a known good (brand new) coil, when that turns up. im still on the look out for an ISV. im going to try replacing that first before i move onto the maf, as ive said, it doesnt make a noise on ignition, aparently its supposed to buzz? anyway, if i get the chance when i get in from work tommorow morning, ill do a bit more electrical testing. Im also going to try contact grease on the MAF, and have a go at closing the pins in the plug up a bit and see if that cures anything :bonk: Quote Share this post Link to post Share on other sites
Kevin Bacon 5 Posted December 2, 2015 Re: the isv, all of the external sensors etc are 12 or 5V feed from an ignition source and the ECU pulls them to ground. If you were to connect the isv across the battery, it should open fully. If that happens, you can outrule the isv. If the 1100 rpm cold idle drops down to 680rpm as it warms up, you can also rule it out. If you have access to VCDS, check the throttle position is Another common idle problem is the noise damper box which contains a poly mesh insert that can get sucked out into the piping, restricting flow. I agree with the MAF though. 9 times in 10 it's the cause of rough running & power loss. Quote Share this post Link to post Share on other sites
