Have some problems with a stock 1,7 D-jet that runs wery lean, hunts and pops in the intake, hardly running at all....reving up wery uneven and slowly.
-Engine has not been running for severeal years so there is no history to tell.
-Timing triple checked 27 degrees at 3500rpm
-Fuel pressure triple checked 31psi
-All 4 injectors new (repro)
-Trigger points checked OK
-Changed to anoter MPS (which runs well in another d-jet) with no difference
-Changed head temp sensor with no difference
-Compression tested, even around 145psi
-Points, condenser, cap, cables are new (also tested with an old set but no difference)
-All injectors getting pulses, checked and injector plugs are at the correct injectors
-Yes firing order is triple checked
The only way to get it running quite OK is to replace the head temp sensor with a potentiometer at 3Kohms, runs quite good with that even when warm.
This leads me to think that it is running w e r y lean for some reason.
Which MPS part number do you have, does it hold vacuum and has it been previously adjusted?
Have you checked for a vacuum leak (or leaks)? Since you already tried a different MPS, looking for leaks is the next thing to check.
If the vacuum and intake hoses haven't been replaced in a while, start there. Also, check the intake manifold (the sheet metal piece that the throttle body mounts to) to make sure there are no rust pinholes in the bottom (fairly common problem, especially when the car sits for a while).
Short work on the engine today again...
Found out that the PCV was fully open all the time replaced it with a fixed 3mm orifice, idle came down a lot, now idles at 700rpm...but it didnt make any difference on the running, still wery lean, bucks and hesitates a lot when reving up, it can take some 5sec for reving up when opening the throttle.
Checked the throttle switch again, it gives about injector 20 pulses from closed to open and is well adjusted.
We ran it fully warm and adjusted the potentiometer (which we have replaced the head temp sensor with) so that it ran with good response. We must have the pot. on about 3kOhm, much less than that and it wil hesitate. 3kOhm corresponds to a dead cold engine!
Something is making the mixture way to lean but what?
(Sorry Jeff did not get the MPS no this time).
Besides the lean condition, are your distributor weights lubed and vacuum advance working?
I was not asking about your ignition timing settings, but are your vacuum and mechanical advance functions working? If not it may be a reason for the lag in revving.
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