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I am getting very frustrated with a stalling / hesitation issue and have put days into fixing this with no complete results. I am parting out a 1985 900 hatch and have a lot of extra 1988 turbo parts laying around. I am willing to reward the first person to lead me to a correct diagnosis of my issue with some free c900 parts! I have many things you may need, or maybe you would just like some valuable spare parts. Things that are reasonable to ship, unless you live in Washington State, then I can bring some awesome goodies to your door.
The car: 1989 900 Turbo 5 Speed
Ran great until I took apart the intake plumbing to fiddle with the bypass valve. After putting everything together, it now has trouble idling and RPM will drop to 0 and stall after letting off throttle and letting off engine load (neutral or clutch in). I can keep it from stalling by keeping throttle partially open (heel-toe-braking :D ). Only seems to be a problem at no-to-partial throttle. Under WOT, the thing boosts and runs just fine after initial hesitation sometimes .. but it is scary driving at WOT all the time in the rain! Cold / warm engine has effect on problem.
Here is my fix attempt process so far:
- Checked and tightened all clamps on intake plumbing (3 times)
- Checked all intake boots for cracks
- Cleaned MAF (AMM) and AIC with MAF cleaner
- Cleaned throttle body
- Vacuum tested bypass valve, FPR, Distributor: all hold vacuum
- Replaced all vacuum lines that start and end in engine compartment
- Replaced and tightened vacuum unions between intake manifold and charcoal canister
- Vacuum tested vacuum line to dash: holds vacuum
- Vacuum tested vacuum line to heater controls: leaks vacuum <is it supposed to? not quite sure. Plugging bung has no effect on idle.
- Replaced 3 intake manifold vacuum grommets and crankcase vent grommet on intake tube
- Attempted spraying all vacuum connections with starting spray, no effects on idle
- Attempted putting tube to ear to pinpoint vacuum leak sounds, nothing found except especially loud AIC hoses. AIC hoses checked all crack-free.
- Cleaned and gapped spark plugs
- Replaced distributor cap and rotor (bosch)
- Tracked down faulty LH system relay, replaced with used bosch relay from parts car
- Tested MAF, now have correct glowing wire
- Cleaned battery terminals, main LH grounds, engine-to-neg-terminal ground with wire brush and electronics cleaner
I have so-far been set on this being an intake / vacuum leak because of the sudden onset of the problem after I was messing with those components and did not touch anything else, but I am now going to do the cap/rotor/plugs/wires thing today, just to be safe.
Am I right in assuming that good power under WOT should rule out insufficient fuel / clogged air, fuel filters?
Anyone have any more methods of testing for leaks in intake tract? I am becoming suspicious of the large-diameter crankcase vent hose that runs under the intake manifold, but I can't think of any way to test it without removing the intake manifold :(
Thank you for reading all that!
posted by 192.188.205...
, Mon, 1 Nov 2010 09:48:05
, Mon, 1 Nov 2010 13:50:59, Mon, 1 Nov 2010 09:46:03, Mon, 1 Nov 2010 17:36:38
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