sharkmeister85

Well, I was hoping to learn a little something about 928's watching and helping Colin on his shark "rescue" project. Guess I'm gonna find out a lot more than I bargained for if we can get this friggin' thing running again. The thing ran fine a year ago. I can't believe a bad sensor could cripple an engine this bad, so I don't think time should be spent checking them. We swapped brains and MAF, they are fine. The idle (if you want to call it that) has lots of black smoke, so too much fuel going in (or not enough air?) The truth is out there. Put the pieces together,....what does it (or should it) tell us?
Glenn

Lizard928

I am thinking it is that the manifold didnt seal to the head, and what I was more asking is if a 87 intake gasket could be used on the 85/86 engines? as they are ALOT cheaper,

heinrich

Try the starter fluid Colin ... see where leaks are.

Shane

With a fire exstinguisher handy just in case.

lorenolson888

Hi,

Sounds like you tried the MAF in another 85 car and it worked there...but diconnecting it has no effect in your car...

Buy the proper gaskets and sleeves for your 86 intake.. Of course replace all of the rubber that looks bad in you PCV systems ... small vacuum lines... and hoses in the intake...

928 110 566 01 You need two of these paper gaskets... they are $5.50 at devek... I think the expensive one is metal you don't need that... just use some liquid gasket maker and the paper/fiber ones will seal for another 20 years...

The aux air reg or idle stab is definitely a source of problems.. ~$150... but try some liquid wrench or wd 40... maybe it is stuck in the closed position.... this valve is responsible for a lot of idle surge/pulsing/instability problems... and if stuck shut... (from not being driven lets say) then a rich runnig poor idle or low idle would be characterisitic...

My 86 car ran identically with the MAf connected or diconnected.... reall rich... black smoke and soot... soo much black smoke that it would burn my eyes if I ran it for more than a minute in my garage...also my garage was covered in soot.... I keep a PC (now black and sooty) in there to look at the manuals on CD etc... But replaceing the MAF and O2 worked well this was 95 % of the problem... Plugs,wires dist etc was also the problem but minor in comparision. Do you have an O2 sensor and is it the same as the 86 in you 81 euro donor tub...

Did you take the O2 sensor and cat from the 86 and transplant it also...

The part # is 928 606 128 00 for an 86 o2 sensor... the harness from the 86 should have a plug for it... in the pet guide there is no part number for an 81 ROW(non usa canada) of sensor... thought the picture seems to show something... It is worth looking into... sensor problems are pretty common at this age and they do not last forever... even go bad as they sit.... My car had MAF and o2 simultaneously wrong so it made diagnosis a real bitch... but an 86 USA engine is a kick in the pants when running properly.... so keep trying and spending... O2 sensor is $150... call devek... MAf is a bit more so testing against other peoples is a good idea...

Please let us all know how you progress.... These old strings will help others in your predicament and add to the knowledge base....

Loren Olson

lorenolson888

Hi Lizard... I reread and your O2 sensor is new... and for an 86... so i imagine that it is not the problem...

Idle stab.. maybe... make sure that the throttle switch reads well in the idle position...

The symptoms sounds like the car is ignoring inoput from the various sensors and just running like the flat 5ms pulse width... you mention the engine will not rev... so it just bogs down and stalls...

How did you reseal your intakes.... is it all new???

LO

Lizard928

I will try to take off the idle stabilizer valve and clean it up, but i doubt that is it,
I am going to try some starting fluid to see if I can find any leaks,
I dont think that the rubber boots are leaking on the intake but the starter fluid will prove/disprove that,
I thought that in the limp home mode I still should be able to rev it up, and also with the limp mode at partial throttle it should lean out,
as for the TPS it does bridge 2 of the terminals indicating that it is reading that the throttle is shut entirely,
Loren, have you watched the video?
as for the MAF, we didnt try mine on another 85, we tried 1 that was taken out of an 85 that ran, it was removed iirc about 6 months ago and had been sitting on a shelf with the plastic caps on it.

Lizard928

I have tried the starter fluid and it doesnt make a difference to how it runs at all, so I now thinking that it is unlikely I have a vacuum leak on the intake,
does anyone know for certain if the 86 engines have a hall sensor? as I dont see any area for one on mine,

Heinrich seems to think it is a ign issue,
the other question is there only the 1 pickup for both computers off the flywheel? the TDC sensor connected to nothing origonally, and I dont have any other sensors that I am aware of,

in regards to the idle stabilizer valve, when I unplug it the idle drops down even lower, I am estimating about 500rpm MAX, and I pull only about 12.5 where when I plug it back in I am getting roughly 15, and the idle rises up dramatically, also when I had the intake off to have it powder coated, I had this taken off as well, and it was perfectly clean inside, with it raising the idle when it is connected is it still possible it is defective?

whall

Lizard,

The symptoms sound very similar to what I had on my car. Mine turned out to be bad plug boots at the distributors. Pull the boots out of the distributor and make sure the ceramics are in good shape. Even better is replacing them - if you want to know my source, send me an e-mail. I got a great deal on the wires.

Lizard928

Hey Whall,
I am going to be replacing my leads shortly with Aurora 8.5MM leads, that have a lifetime guarentee,
I inspected all the origonal leads and all the ends seam to be fine except for 2 the #7 and #8 they have abit of corrosion in them,
however I am going to be getting those leads very shortly.
I am off to go and test the spark with a light and see roughly what the RPMS are actually at.

Lizard928

Well I checked the Temp II sensor and it appears to be within specs as does Temp sensor I, and the TPS reads both WOT and closed throttle so it is working,

however the sensor by the oil filler neck in the intake manifold doesnt let anything through, neither does the sensor in the water channel right by the passenger side dampener,

I checked the timing as well and it is jumping around ALOT,
http://www.geocities.com/cjensan928s...S/MVI_2453.avi the light is set to 12 deg BTC, so effectively OT on the balancer is 12 deg. for a video of the timing light, you may be able to pause it and move it for and back to be able to see exactly where it fired, I saw that when it first started it was roughly 43 DBTC, but I saw another flash where it was almost 43 DATDC, so something is causing the timing to jump around ALOT,
I dont think that the computer would have the ign that far retarded on a deaccel for emissions.

any ideas as to what would cause it to jump around like this? defective RPM sensor off the crank? bad ground(s)? or bad computer(even though it ran fine in another car)?

lorenolson888

I bought a set of kingsborn blue wires... thru devek... All beru hardware... I'll let you know in a couple of weeks how they go... If your wires were as crispy as mine it is definitely time... but mine were working fine.... I just think that after 19 years it is time and it couldn't hurt...

The O2 sensor is the 86 USA part number? right... remember the O2 sensor is the one that all others are trimming to...

I do beleive ther is a hall sender..let me try and find out...

I am not sure if 86 engines (like mine and yours) even limps home... Some one has told me that only 87 and newer cars have limp mode (35 pin connector as opposed to our 25???) But someone has told me that the injector timing would run at 5 ms at less than 2000 RPM and at some longer pulse (not sure what time) for over 2000 RPM. My car did run oddly up to 2000 and then get better right at 2000. then it would run odd at 4000 plus maybe it was leaning out. The MAF and o2 sensor was the problem... seemed to be limping... Not sure...

I agree idle stab sound like it is not stuck and that it is responding when you unplug it... I have heard that it can cause the cars idle to wander up and down and cause stalling when one lets off the gas suddenly. like at a stop light... but yours is not revving at all...

Not sure what statethe idle stab goes to when unplugged... sounds like it closes... does it run richer???

The intake ...I am not sure about the testing for leaks by using starter fluid but that sounds plausible...

Ignition sounds like a place to at least be looking... The inability to actually rev up sounds like it could be an ignition problem... but it asounds like it does run...

But if your car is running really rich it also may not be able to rev... does it ever get past 500 rpm??? like to 2 or 3 K ..

I can't find the video... Which posting is it???

LO

lorenolson888

That was interesting...

It may be hard to get a perfect idea if timing if it is running really rough at low RPM... You understand why... but that does sounds like ignition is a good place to be looking... Wires all in right place? No moisture or or really bad corossion??? The wire tends to go at the junctions I have heard... but breaks in the middle may be possible... Coils are good??? I have heard that if you spray windex at your engine you can sometime see arcs at leaky wires...

I agree the engine should be running... but at the same time obviously something has gone wrong... So Test as many hypotheses as possible and is convenient... one should be able to fix it... You pulled the whole engine and wiring but maybe something has weakenend by sitting or during the move....

The computer is good too huh? Hmmm Probably not that either... since it ran I would not guess that it is multiple problems...

The crank sensor is not a bad place to look... Anyone out there know about crank sensor?

lorenolson888

Hi I can't get to the videos...

LO

Andre Moore

Lizard, 85/86 engines don't have the hall senser. Instead they use vac advance on the control unit. Have you checked all of the ground supplies for the engine harness?