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I am making a new post because now I have new or worse problem and some new information. My original post was ‘Stumbles and misses on acceleration’. 1988 Saab 16 valve Turbo convertible, it consistently stumbles when accelerating and sometimes may stall; it might be hard to restart. The car has 153,000 miles, garaged, well maintained. When I initially start the car up cold, it starts right up and idles perfectly. Sometimes it would stall and not start; however, after a short period of time it would start and idle fine.
To recap I have put in new Bougicord wires, new NGK plugs with proper gap, and Bosch cap. I put in new Bosch fuel pump with working pre-pump, new Bosch fuel filter. Checked both fuel pump relays above ECU- OK. I have switched out the following components, ignition control module, AMM, ignition coil, APC control unit, and ECU. I have gone over all of the turbo plumbing with a fine-tooth comb - no leaks. All vacuum tubing seems to be in good shape - no leaks, turbo bypass valve / hooter valve OK. I have switched the Fuel Pressure Regulator and installed a new distributor Hall sensor. Just to be sure I did not have some ‘bad’ gas. I drained all of the fuel out of tank and put in 4 gallons of high octane gas.
Now the symptoms have changed drastically, it is difficult to start, much cranking and then when it does start it has a rough idle. I just got the fittings I needed to install a fuel pressure gauge on the fuel rail with a hose running to the gauge I placed on windshield so I can view while driving. Which a week ago I could attempt but now it is running so poorly I would not even attempt. This morning when I started the car the fuel pressure initially was about 12 PSI and gradually went up to 28 PSI. It is a Harbor Freight gauge so I am not sure if calibrated correctly. After running 5 -10 minutes I noticed that the fuel pressure was gradually reducing from the 28PSI; when it got down to 15 PSI the car stalled.
Because it was idling roughly, like not hitting on all cylinders, I did a test again to check the injectors. I restated the car and I pulled off the number 4 injector connector and it made no difference in engine speed. I reconnected 4 and then removed number 3 connector, again no difference in engine speed. However, when I took off 1 or 2 injector connectors the engine would immediately stall. Later when I tried the experiment again, 3 and 4 injectors would seem to act correctly and slow the engine. I think all 4 injectors get their signal to fire at the same time. I suppose the injectors could be clogged however not sure why it would be inconsistent, sometime affect engine performance and sometimes not.
So I have 2 questions, what should I check regarding the gradually lowering fuel pressure? And what might be causing the strange issue with the injectors?
As always helpful suggestions would be appreciated.
posted by 76.181.107...
, Mon, 18 Oct 2021 19:40:57, Wed, 13 Oct 2021 16:32:55
, Wed, 13 Oct 2021 09:14:18, Wed, 13 Oct 2021 14:02:08
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