Member
So my car has a hunting Idle after about 45min of driving or after it sits for an hour and I try to restart it. It will start perfectly fine after after it cools off so about 5 hours. There is a strong smell of petrol when I try to start it up when its cold, I think bad o-rings on my injectors, (hates cold starts). I've replaced my ICV, Purge Valve, fuel pressure regulator, fuel filter and also upgraded to the miller gen III MAF, I'm doing a fuel pressure and vacuum pressure test tomorrow as well as a smoke test. I have also done multimeter tests on all of the connectors of parts I replaced.
I have been lost trying to figure this out for the past month.
Any solutions or other threads that go over this issue (I have already gone over lots of the threads for idle problems or stalling issues).
Member
Hi from QuebecI don't have a solution for you unfortunately but I just wanted to say that I have the same issue on my 735iL (same engine as your car).
In fact I just placed an order for new Bremi spark plug wires in the hope that it will fix my hunting idle.
I will be following this thread, hopefully you can find a solution!
90,700 miles 1992 BMW 735iL Azure Blue Metallic with Silver Grey leather interior ‣My car ‣My YouTube channel
Member
Have you looked at swapping the MAF over for a known good one ... ??? Also be interested to see results from vac tests ... that is often a cause of hunting ... ...
Member
Given a stock set up I'd say just a vacuum leak that the ICV is trying to deal with. Given the MAF, ??
If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue
Member
Okay so I did a smoke test and found that I have a leaking valve cover gasket. I also did a vacuum pressure test and came out with 14psi at 1000rpm. I have tried it with both my OEM MAF and the miller gen III and still the problem continues.
Member
More news, after driving back from my school it has started backfiring upon stepping on the gas to hard and has horrible throttle response now and also bogs down when you ease onto the throttle
Member
Did you plug the AFM back in?
O o
/Ż____________________________ ______________
| BLAAAAAAAAAAAAAAAAAAAHHHHHHHH! !!!!
\_ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ ŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
Member
Originally Posted by Joe.f
What?
If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue
Member
So I did the vacuum test and the idle was jumping around 900-1200rpm and the PSI was jumping around from 11-15PSI so I held it steady at 1000rpm to stop the hunting and the pressure evened out to give me my 14PSI reading.
Member
The measurement is inches of mercury, or in/hg. 11-15 is low, suggests a vacuum leak.
Member
So more news, I installed a inline fuel pressure gauge and the pressure started at about 40 psi and then sat around 38 psi after a little bit of driving and when it started to hunt the pressure didn't change. So just wondering if anyone has any ideas from hearing that on what my problem is
Member
Yeah, no one is saying it outright but you have a big leak. Did you fix the valve cover?
there’s also a tiny gasket at the rear of the head that can cause it too.
You also need to check the tube running into the idle control valve, vacuum hoses, and the vacuum tube going to the brake booster (if you have vacuum boosted brakes).
Member
Ok I'll do another smoke test, I did the valve cover and that was the only spot I had a leak but I'll do another one to make sure I didn't miss any
Member
Again if you have vacuum boosted brakes I can tell you from experience that the booster can leak internally and cause a vacuum leak but not show up with a smoke test.
Member
Okay, thanks I will check and then get back.
shade tree mechanic
Moderator
also check the ground cable from engine to chassis,
Shogun tricks and tips for the E32 series are HERE!
Posting Permissions
Reply With Quote
Bookmarks