Now my 92 Volvo turbo wagon is not running!

It has the LH Jetronic fuel control system. THis is very strange. I was running around town when it began to die when I released the gas pedal....the idle was gone. Then it rapidly progressed to where the car would sort of start, but very rough, and then since it seemed to have started, I released the key, and it immediately died without ever accelerating any. When troubleshooting it the next day, the leak had temporoarily lessened to the point that it would start and run, but rough...so then I was able to hear a leak,locate, and fix it. A rubbber cap I had installed on a tee on a vacuum line coming off the intake manifold had deteriorated and split, and so it was sucking a lot of air....you could her it. So immediately after replacing the bad cap, then the car ran perfect again. But,,, in the evening of same day, my wife tried to drive it, and it would not start again! And it was the very same symptom again. You hear it beginning to catch.... the cylinders are firing, but very rough.... and so you release the key and a second later it dies, without being able to accelerate. If you don't give it gas, it dies; if you DO give it gas, it still dies. Every crank you get the same thing. So I put my fuel pressure guage on it, and there is good pressure. I put my vaccum guage on, and at the point when the cylinders fire for about a second, maybe two, before releasing key/engine dying, the guage stayed at ZERO. So....how could it be that it just happens to spring another massive leak? I had a problem similar to this last year, and there was a barbed union on the inlet tube to the idle air valve where one side of the tube had come loose, causing a masive vaccum leak. I checked that again, the whole length of it on inlet, and the other side, and it seems OK. I looke at all the vac lines in the top of the intake manifold, but I found no leak, and now you do not hear any tell-tale hissing. THe ECU is not setting any codes, either. SO...what to check next? I am still suspicious that it is a big vaccum leak, as with the engine firinng/sputtering like that for 1 or 2 seconnds, it sieems like I should see the vacuum guage kick upscale some.....right? Should it show a little upscale movement even when just cranking? I ckecked the timing, it has not changed. Any ideas?

Reply to
geronimo
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First thing I would try is unplugging the air mass meter. Also check all the plumbing between the airbox, turbo, intercooler, and intake manifold, the symptoms are what you'd get if any of those pipes were disconnected.

Reply to
James Sweet

vacuum line to the power brake booster? Or perhaps a ruptured diaphraghm inside the brake booster itself?

Reply to
Perry Noid

BINGO!!!!! It's the AMM as you suggested. I never would have thought to try disconecting it, after all the ECU wasn't setting any codes. I disconnected it, and then the car started and ran...but the idle is only at 300 RPM, it just barely keeps running at idle without the AMM....but this allows the car to run, and when you rev it up, it is fine. And of course the CHK ENGINE light came on with it disconnected. Sheesh...that sure is an expensive part though! On the bright side, I shudder to think how much I would have paid to have this repaired at a shop....they would probably have put hours into it in labor, and probably doubled the price of the part.

THe car ever since we got it a couple of years ago, is getting poor gas mileage. it's only about 17 even on highway. I know that since its turbo that probably reduces the MPG some, but still shouldn't it be in low 20s? I am just wondering if that AMM could have gone off-spec causing poor mileage, before completely failing. Perhaps not, as it would show up in the mixture being too rich I suppose. I had a shop check the mixture and timing not long ago, and they are OK.

Many Thanks, Geronimo

Reply to
geronimo

There's a good chance your mileage will improve with a new one. They often fail in such a way as to not cause the computer to complain, but one day the car will simply not start.

I once got better than 31 mpg in my 740 Turbo, that's with a manual transmission and was mostly highway and driving with a very light foot, but you should be able to manage 24 mpg highway without too much trouble, and certainly better than 20.

Reply to
James Sweet

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