chrispy Posted August 23, 2005 Share Posted August 23, 2005 Thank god I found you all again, thought I'd lost you... OK, so this is similar to another post on here, but my symptoms aren't quite the same. My 1992 Vogue SE 3.9 has a few idle issues and I'd love to get your feedback. When I bought the car, I was informed that its CO emissions were high (around the 5% mark), and the previous owner thought the air flow meter might be to blame. I've also noticed that when started (cold or hot) the engine revs to around 1500-2000, then drops to almost stall, then revs high again. This cycle repeats a couple of times before settling down. When settled, the idle seems a little lumpy (always thought V8s should be smoother). While still cold, stepping on the accelerator causes the engine revs to drop to almost stall, before recovering and revving as you would expect. This will go on for a couple of miles or so. It never actually stalls, but it can be a bit nerveracking in traffic. I've cleaned the stepper motor and the hunting on start-up has improved (revs to 1500-2000 then settles at around 5-600), but the initial almost stall on acceleration is still there and the rough idle is still a problem. I've checked for leaks on the air intakes and the various bits of pipework and nothing is evident. There is a distinct smell of petrol after a good run (around the rear of the car), which might indicate that it's running rich (not sure, not an expert) and I'm pretty sure it's drinking an awful lot more petrol than it should. Any help would be most welcome... Chris Quote Link to comment Share on other sites More sharing options...
Mean Green Posted August 23, 2005 Share Posted August 23, 2005 Hi Chrispy. The symptoms you describe are almost the same as those in my other post. I am not further forward with it, getting really annoyed by it now! Quote Link to comment Share on other sites More sharing options...
ariane44 Posted August 23, 2005 Share Posted August 23, 2005 Hi Chrispy! Does your car start immediatel when warm (parked for about 30mins)? Do you notice any difference, when you unplug the O2 sensors or temp sensors (water/fuel)? In case you have curise control - does that one work? Are any spark plugs darker than the others? Are the symptoms changing (better/worse) when you disconnect the battery for some time? Maybe these can help you. Cheers Carsten ;-) Quote Link to comment Share on other sites More sharing options...
chrispy Posted August 23, 2005 Author Share Posted August 23, 2005 Hey Greg, I sympathise and read all the replies to your posts with the hope of finding some clues. Maybe we should start a 3.9 rough idle support group Carsten, my Rangie almost always starts immediately, though the other day I left the fuse for the air-con in (only way to turn it on and off, different story though) and she didn't want to start at all. Just revved to 1500-2000 and then immediately stalled. Pulled the fuse out and she started first time, hunted for a bit and then settled. I haven't tried unplugging sensors... Cruise control works fine... Haven't checked plugs... What will disconnecting the battery do? Will that reset the ECU in some way? Thanks for the link, none of those things are in my workshop manual Will print them out... Cheers, Chris. Quote Link to comment Share on other sites More sharing options...
jwriyadh Posted August 23, 2005 Share Posted August 23, 2005 Finger trouble. jw Quote Link to comment Share on other sites More sharing options...
jwriyadh Posted August 23, 2005 Share Posted August 23, 2005 Chrispy, You seem to have similar symptoms to Mean Green, and you have extra too! You also mention apparent richness and the fact that the A/C appears to affect the starting and running of the engine. Your ECU appears to have lost control of both the air supply and the mixture. If you want to fix it then you need to follow a logical path, as in; Check ignition and timing. Check power supplies. Check fuel pressure. Check air control. Check mixture control. jw Quote Link to comment Share on other sites More sharing options...
ariane44 Posted August 23, 2005 Share Posted August 23, 2005 Hi! Maybe we should start a 3.9 rough idle support group May I stay though having a 4.2? :-)) Carsten, my Rangie almost always starts immediately I had leaking injectors when it was hard to start hot combined with a smell of unburnt petrol. Got a set from five-o (Bosch injectors, less than 200GBP for a set of 8). I haven't tried unplugging sensors... This helps to see if they affect the running. Testing them is described in the above mentioned test sheets. Cruise control works fine... So you have vacuum available. The same vacuum is used in the stepper motor. What will disconnecting the battery do? Will that reset the ECU in some way? It will erase any faults. Thanks for the link, none of those things are in my workshop manual Will print them out... Cheers Carsten ;-) Quote Link to comment Share on other sites More sharing options...
Niall_CSK Posted August 24, 2005 Share Posted August 24, 2005 So you have vacuum available. The same vacuum is used in the stepper motor. Actually no, the cruise control uses it's own vacumn pump situated on the nearside front inner wing. Engine vacumn is used for dizzy advance & heater recirc control only. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted August 24, 2005 Share Posted August 24, 2005 PM Me your e-mail address - if your on Broadband I'll send you my diagnostic manaual You've done much of the obvious std stuff, now you need to systematically work through whats what, just remind me of the engine (hotwire or Flapper) so I send you the right stuff ! Nige Quote Link to comment Share on other sites More sharing options...
ariane44 Posted August 24, 2005 Share Posted August 24, 2005 So you have vacuum available. The same vacuum is used in the stepper motor. Actually no, the cruise control uses it's own vacumn pump situated on the nearside front inner wing. Engine vacumn is used for dizzy advance & heater recirc control only. Why then would there be a vacuum line from stepper motor to cruise control on my '95 4.2? Maybe the design has changed with the serpentine belt models? Cheers Carsten ;-) Quote Link to comment Share on other sites More sharing options...
Niall_CSK Posted August 24, 2005 Share Posted August 24, 2005 Maybe, I never noticed that on the 95 MY I looked at. What are you referring to when you say "stepper motor", does that MY have a a stepper motor for the cruise throttle actuator? Earlier ones have a simple diaphram/rod actuator. Quote Link to comment Share on other sites More sharing options...
ariane44 Posted August 24, 2005 Share Posted August 24, 2005 Stepper Motor = thingy on the rear of the lenum which adds more or less air when ideling. CC is acutated by a diaphragm, mounted right of the plenum. I will look at my Range again as soon as I have it back here, may be I did not check the lines carefully enough. Cheers Carsten ;-) Quote Link to comment Share on other sites More sharing options...
Niall_CSK Posted August 25, 2005 Share Posted August 25, 2005 See what you mean. Up to 93 the idle air control valve / stepper motor definately only has an electrical connection. The only other hose I can think of in that area is the one between the plenum chamber and the fuel pressure regulator, this is supposed to ensure that pressure is maintained under sudden high demand, high vacumn. I didn't mention that one as it's on my list of hoses to check but it is worth mentioning as it often gets forgotten about tucked away at the back. If it has failed it can have the effect of reducing performance by both a week mixture & low fuel pressure when you need it. Interested to hear what you find. Cheers Quote Link to comment Share on other sites More sharing options...
ariane44 Posted October 24, 2005 Share Posted October 24, 2005 Interested to hear what you find. It took some time for me to look under the hood, I admit, but finally I found that you were absolutely right. It looked as if the vacuum went into the stepper, but it does not. Cheers Carsten ;-) Quote Link to comment Share on other sites More sharing options...
chrispy Posted November 17, 2005 Author Share Posted November 17, 2005 Well, in the end I got tired of hunting for vacuum leaks and took it to a garage. Turns out one of the temperature sensors was dying and the timing was way off. Problem seems to be cured now Thanks for all your help, Chris Quote Link to comment Share on other sites More sharing options...
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