1998 2.8 30v idle/stalling issue

inhen · #1 10th May 2015, 10:31 PM

Greetings all,

I have a head-scratcher for your consideration. A couple of months ago I rebuilt the steering rack after a catastrophic failure of one of the internal seals and carried out a sevice. Not long after the engine started stalling when braking for junctions and when manoeuring at low speed but only once up to temperature. The idle seems to be lower than usual and ocassionally rough. Perhaps unrelated. No fault codes recorded and the problem is getting worse.

I have replaced all of the PCV and vacuum lines and associated valves and stripped and cleaned the throttle body. This has helped the rough idle but once I had put everything back together I went for a drive and once the engine was warm it stalled coming to a stop at a junction and again while reverse parking.

I would love to roll my sleaves up and get in to it this week but its looking like im going to havebto work so any ideas will be graciously considered.

Regards Ian

steamship · #2 11th May 2015, 10:35 AM

Ian, I had similar problems to this last year on my '01 3.7. Some of my vacuum lines had disintegrated completely, but I also had issues with the ABS and Traction control lights coming on. After some searching on here, someone suggested turning the air-con ECON switch off. From memory, with it in the Off position, the engine runs slightly higher in RPM, so preventing the stall.

B@fink · #3 11th May 2015, 05:58 PM

Mine started doing something similar. I had a non start a couple of weeks back (the battery cables on the inner wing had corroded)and I had to disconnect the battery for a day to fix and clean them. After that it wouldn't idle properly when warm, it was slower than it was before I removed the battery. Only thing I could think of is it's the throttle body adaption that goes out of the window when the battery was off. It was perfect before the battery disconnect. I did a throttle body reset and it's much improved (not perfect but idle speed is back up to near normal when warm). I'm hoping that it'll relearn it's settings after a bit of driving about to finish sorting itself out.

inhen · #4 12th May 2015, 11:20 PM

Thanks @steamship I've been driving with the climate control on ever since this started to keep revs up. I don't ever press the ECON button anyway, that's the one that instantly mists the windscreen up right!? I also have the ABS light of doom issue, I think it's a wiring loom problem as I've tested both sensors and cables and the ECU connector seems fine too.

B@fink I also got this issue after the local garage fitted a big battery for me (for warranty purposes) come to think of it. Since I've replaced all the breathers and vacuum hoses and cleaned out the throttle body I went back to the garage to consult the VAGoracle. He insisted that TBA was not part of the service when changing a battery and shouldn't be necessary. But, he has agreed to do it for beer tokens with his own VAGCOM as mine is read and reset only.

I did notice when I stripped the throttle body that it's an encoded stepper motor so why it would need realigning I don't know. Hopefully it will help, the best 0-60mph I've recorded is 9.4seconds since all this started!

I noticed that the hose on negative/engine side of the TB that gose to the valve behind the air filter housing then in to a solid pipe disappears off under the back of the engine. Does it go to the gearbox or ECU? Or somwhere completely different?

inhen · #5 13th May 2015, 02:25 PM

Throttle body realigned... problem solved! Car idles perfectly, hot or cold, revs never drop below 800rpm when braking or manoeuvering and most shockingly gear changes no longer resemble being rear-ended by a bus!

Thanks guys and thank you Malcolm at F1 Bedford.

Now some time off work to strip the turbos on the 300 yay