More 929 woes... missing on morning start in hot weather

[jc179]

Hi everyone

I have a 1990 929S - its been running great until lately. Sometimes when it rains it will miss, and have very reduced power. Today its +25 outside, and on a fresh start (car was fine yesterday) - it fired right up. When I started off down the street there was a noticable loss of power. The engine is badly missing, but its not too obvious at idle.

Are these cars known to have any sort of issue to this problem? I don't get a cel, and I drove it for about 5 minutes with no change. When I pop'd the hood, I would try quickly snapping the throttle open, of course it stubled for a second then the revs quickly climbed. The one time it stubled it backfired into the intakne.

Today it's a little humid out and we did have rain yesterday although the car was fine.

I'm thinking it's a HV issue - the plugs, wires and dizzy are new. Could my coil be going bad? Is there a way to test. Could fuel pump not be delivering enough psi for the higher rev's

Anyone have any ideas? Sort of stumpted!


Thanks !!

JC

[Netopia]

You might need to check you dis. cap. it could be getting a little bit of moister

When was the last time you changed your air filter and did a tune up

[NoD]

when i check the dist cap, take a look at the seal, if that is broken moisture will accumulate.


to test the coil u need a multimeter.

primary resistance should be 0,72-0,88 ohm
secondary resistance should be 10-30 kohm

measured at 20c or 68f

primary is the + and - input of coil
sec is -+ and coil output

U replaced the dizzy, u sure the timing is correct?

could be gaskets,hla,valve,fuel, ignition, sensors.
but start with air leaks, timing, function of the maf.

[jc179]

Hey

Thanks so much for the good info. It sounds like I've gotta check the dizzy again and that seal! I have to pick up a shop manual to verify the timing - but haven't had any luck finding one, can you suggest one or even who writes one? The local shops don't have any haynes...shudder, and I don't know if Bently ever published one?

Also,

I'm not familiar with what you mean by hla, and by valve do you mean egr valve .... the dreadful one at the back of the engine?

pps - Are there any technical details for what all the solenoids and sensors are on the top of the head, and a vacuum diagram? There are *so* many on the S engine under the top cover... I've been able to find some documentation for the non-S cars but S seems to be a bit hard to find info for!


Thanks in advance!


Jonathan

[NoD]

i think chilton made one, not sure if they made one for the 929s.
But the best would be orginal mazda workshop manual.

ive seen a couple on ebay.
1990 Mazda 929 929S Workshop Manual 012005

[Netopia]

Check the ICV if the start to go bad your car will runn like crap

[mazdaspeed929]

You could sign up for Alldata. It's an online shop service.

[Netopia]

That is a waste off funds to just get a answer

[jc179]

Hey everyone

Thanks for the info. I will look into that ISV valve. I've ordered a manual, hopefully it comes !

Cheers

JC