linderpat

I'm in the middle of quite a bit of research on the board, but thought I'd post a couple of specific questions here.
MY 86.5, had the intakes off to access engine bay to replace power steering reservoir and hoses. Put it all back together to fire up engine in order to start car and turn wheel (part of flush procedure). Cranks strong, but no start. Thus, either fuel or spark right? How do I check for spark?

Also, I had the left side coil wire off when re-doing the ps hose. Could it be somehow misaligned? It doesn't seem like that could be an issue.

Also, I'm getting strong fuel smell. Car acts fuel starved tho. It wants to start and almost catches, then dies

I had cleaned the bottom of the engine and in and around the front of the engine with simple green and water, but that was 2 weeks ago - should all be dry now. I was careful to keep things wiped down real well when I was doing the cleaning, but maybe that is part of the problem?

Car has always fired right up - have never had a start problem.
btw - car has good gas and battery is fully charged...
Thanks in advance....

Dean_Fuller

Easiest way to check for spark is pull one of the plug wires off the plug and if you have a extra spark plug snap it into the loose wire. Just let it lay on the intake and crank. You will see spark or you won't.

Double check jump post wire connection is nice and dry.

mcholdfast

Sounds like what one of mine did when I reinstalled the intake and didn't have the gasket seated properly. On the passenger side rear, the intake gasket had gotten caught on something when I installed the intake and created a massive vacuum leak. The car would fire and then shut down immediately.
I hope it's something this simple. Good luck.

Landseer

Ed, by coincidence we are in battle with an early 86 no-start. Been working in the cold for 16 hours now, no answers.

We were checking spark simply by clipping a timing light to the plug wires. Tried 1 from each distributor, to also defacto check for coil function. Got light, not sure of intensity.

We bought a noid light (Lisle makes one, got it at an independent parts place) and got injector function on 4 and 8, the easy ones to reach without pulling the plenums.

What have you checked so far? Are you getting any ignition at all?

belgiumbarry

just as written : spark ? wet plugs ? the combination should fire at least ...

Mike Frye

Strong smell of fuel? Did you check/replace the injector O-rings? My old ones were brittle and I'm sure wouldn't have sealed up again. Maybe you've got a leak at one or more of these.

I'd recommend making a pressure test rig and testing it all out before cranking it over again, especially if you smell fuel.

linderpat

Thanks for all the input thus far. I pulled a plug, and it wasn't wet, so no flooding. It did have an oily residue on it, at the threads - Normal? It wasn't fouled. The plugs have about 6-8k miles on them (I replaced all plugs and wires when I got the car in late '06).
I rechecked all the rubber boots on that PIA plenum (anyone want to trade for a model year of other than 85-86? These things suck to work on with all of that plumbing). Anyway, it's all sealed tight.
As to the o-rings on the injectors, I did a whole top end and intake R&R last winter, and the car has been running great. New injectors, all new rubber, vac lines, rings, etc.
One thing Chris - I have the air cleaner housing off and the sensor in it is unplugged - at dinner, while looking thru the WSM (I have a complete set - worth their weight in gold), this unplugged air flow sensor may be part of the no start issue. I will plug back in and recheck tomorrow. The battery charge is good.
One other thing I did - when I pulled the left side coil to move it out of the way for the R&R of the ps return line, I cleaned the ends of the coil wire that runs from the coil to the distributer. I did both ends, and used contact cleaner and q-tips, up in each shroud on each end of that short cable. Hope that's not the problem? I pulled it off and looked at it, and plugged it back in nice and snug.
If it doesn't fire up tomorrow, then it's the relay route to check for fuel flow, etc. It is cranking nicely Chris - not slow and not too fast. It feels like it wants to catch, but it just doesn't. What are your symptoms?

Landseer

Ed, similar symptoms. Time for some deep reading, did the easy stuff. Am following the GTS Died thread closely, similar troubleshooting occuring there.
Your thread, but I'll insert what we find / any learnings. Lots of searches to do on renn today,also. Need to start ohming stuff I think.


Get some chugging, wants to catch. Almost like only half the cylinders are hitting and/or timing on a Buick where you turn the distributor 20 degrees and it won;t start.
Getting a little smoke from both tailpipes. Half-burned gas smell. Fuel pump clearly running. Excess gas I think, not starved, not sure though.



Here's what we tried 2500 miles away...
Changed the crank position sensor with a new one. No change. (thought it might be the connector).

Tried the MAF from the 85, no change. (unknown if it works --- not the best data point, looked good though, fine anenometer wires look intact)
Tried with and without the air temp sensor on air cleaner housing. no change.
Pulled all the 53 relays and cleaned terminals. Pulled all fuses and cleaned ends (very corroded). No change.

Pulled Temp 2 Bosch-style plug to get to the sensor. Got about 5.6 ohms on one terminal to ground, 5.8 ohms other terminal to ground. About 11 ohms measured across them. Measured on the 2000 range scale. Same values on 85 sitting next to it (remember, not a known runner). Not sure what proper readings are. Hunting that now.

Time to go to manuals.

Suspecting one coil or whatever drives it, Temp 2, MAF harness plug short (manipulated it a lot). Very much a puzzle.

Ours just emerged last week from intake refresh & belt remove/retension & Porken timing. Brand new wires. End cap of one coil had come loose when changing coil wires. New injector rubber. New fuel hoses. Ran absolutely exceptionally. Moved it on the driveway Monday. Sat in the rain and cold a couple days. No start Friday or since.

Am first going to check gross timing in case a gear loosened. hope not. Will start with notch check through inspection holes.

Landseer

Ed, trying to help you and me here. Hope the experienced guys chime-in on your original post.


I don't know how to quote people's posts. Here's one from Wally dating back to 2003 regarding an 86 no-start cold:

"Temp II Sensor
This is a dual-element temp sensor mounted on the top front of your engine. Inside the sensor are two independent sensors, with one telling the ignition ECU the engine temp, and the other telling the injection ECU the engine temp. (Earlier cars have only one sensing element.)
Find the sensor. It is screwed into the top of the engine, just to the right of center, at the front. Remove the wire lock before trying to unplug the harness.
On the top of the sensor, inside a rectangular recess, will be two small pins. Measure the resistance from each of these pins to the engine. Do not measure the resistance between the two pins. The resistance should vary with the engine temperature (not air temp).

32 deg F resistance should be 4400 - 6800 ohms.
59 deg F to 86 deg F, resistance should be 1400 - 3600 ohms.
104 deg F, resistance should be 900 - 1300 ohms.
140 deg F, resistance should be 480 - 720 ohms.
176 deg F, resistance should be 250 - 390 ohms.
If the resistances at the sensor are correct, reattach the wire harness and then repeat the measurements between terminals 2 and 5 at the disconnected LH multiple pin plug. In other words, pull the large connector off of the injection ECU and check the resistance there to see if there is a problem in the wire harness.
If the injection ECU (the LH unit) is not connected to the Temp II sensor, the mixture will be full rich, and the engine will not start or run when warm" Wally Plumley.

Am going to try to check the sensor harness, reading at the ECU, because the sensor seems to measure ok.

linderpat

Chris - the common problem between your no start and mine is the coil manipulation. I had the coil wire off, and the end of the coil itself was loosened. If you have a known good to swap, that might be a quick and dirty test?

Also, you probably found this one early on too, but here is a good thread: https://rennlist.com/forums/928-foru...not-start.html

Jadz928

Ed,
Did you do a gross vacuum check on the intake?

Something like this from Nichol's 928 Tips.

Landseer

OK. Visually found a big vac problem, short hose from hard pipe near oil fill spout to the y-connector leading to the brake booster -- was almost off, clamp forgotten. Will check recconnect a longer hose and try again.

Agreed, plenum is PIA.

On my 84 cold start issue, it was time/temp switch. Huge immediate improvment.

Good thought on coil, will have a known-good 944 coil to try in a couple hours (I think its the same).
Can try the unknown condition 85 coils. May take me a little while!

Vac fix / try first.

How do we check coils and coil amps? Are coil amps on front of car near headlight motor?

Landseer

Ed, obvious vac fix did not work so far. More vac tests to perform, thought.

Now checking continuity from Temp 2 into brains.

Next coils.

I need WSM, heads-up display, car-side.

linderpat

Just tried again, everything checked and connected - no joy! Heard the injectors all clicking. Strong smell of fuel afterwards. I'll check relays next, but not hopeful.
Anyway, my teams' in the Superbowl, so eff the car, I'm done with it for today - going to watch TV! (Go Steelers)

Landseer

Go Pittsburgh.

OK. Got it started. What a biatch. Was questioning my Porsche religion.

Unplugged and replugged LH and EZ units. Checked Temp 2 there.
Unplugged and replugged ign amplifiers.
Pulled all plugs, hit them briefly with a torch, torqued them back.
Removed and cleaned the two ground cables from the coil clamps to the motor.
Then, removed and cleaned the ground under the PS, motor to frame.
It started as if something big had changed. Then stopped, then struggled to start. I floored it to start and it finally caught. Held it at 2000 rpm orso. Blew white gassy smoke for the first 3 or 4 minutes. Then trimmed out. Ran great on the road.

Another change: dry and 58degrees when I made the last attempt to start. Not sure if it was the grounds or the temp. Am tempted to replace temp 2 even though it ohmed correctly.

Will see tomorrow how/if it starts again.