I've got a '94 850t that I bought with a motor in pieces. Long story short, the motor wasn't useable, so the car has been sitting for a couple years.

I just got around to putting a motor in it, and I'm having trouble getting it to fire. I've verified the fuel pump is working, and I've got fuel on the plugs, so I've obviously got injectors that are firing.

I did some looking, and came across the official diagnostic procedure. First step was check for spark, which I didn't have. I'm about halfway through the procedure, but I got to the point where I need another person to help, which I don't have at the moment.

I've verified voltage to the coil (12v at the red, ignition on, 9.8 at the blue, while cranking), verified proper resistance through the crank sensor, and that's where I've stopped. However, i have 3 spare coils that I know are good, as well as a spare crank sensor, and a cam sensor. I tried all of them, and still nothing. I'm therefore guessing that my tests will show that I've got a good cam sensor.

What's odd to me is this...I don't have an absolute 'no-spark' situation. I'm using my timing light to check for spark while cranking the car, and every so often the light flashes, the car sounds like it wants to fire, then it just goes back to cranking pointlessly.

I'll keep going with the diagnostic when I have help, but I was wondering if the presence of an occasional spark points to anything in particular, as opposed to a complete lack of spark?

Any thoughts appreciated.
Thanks

 

Have you checked the timing? Not sure but it is possible the distributor is 180 out. Also, make absolutely sure you have the plug wires hooked up in the proper order.

 

I had issues with my 850. The chiltons manual I was using had the order wrong. I used the service manual download from the forums to correct. It ran, but only on 3 cyl...amazing it fired at all.

 

Also check compression. Cars need 4 things to start/run, fuel, air, spark and compression.

 

I normally check compression first thing. My brother has my gauge though, so I haven't done it yet. The motor came out of a car at the wrecking yard that had broken the timing belt. I had to assume it was running when the belt broke. I pulled the head, replaced a couple bent valves, re-ground them all, and put it back together. I can't be sure, obviously, but if I had to bet a paycheck I'd say the compression is good.

As for firing order, it's kind of a moot point right now. I'm getting no spark from the coil.

The more I think about this now, I recall having a computer problem with another car about a year ago. I'm pretty sure I pulled the computer out of this car, in an attempt to get the other one running. What I don't recall though is whether or not the computer in this car is the original one, or the questionable one from the other car I was working on.

The car I pulled this motor from still has the computer in it, so I'm thinking of grabbing that. However, it's a '95. Are the computers interchangable between a '94 and a '95 850t?

 

That was going to be my next guess, I mean trouble shooting proceedure. LOL I'm pretty sure they will work as long as both are same EGR configuration.

 

In almost every case the engine management computer is the very last thing to cause a problem. It's not that it can't fail it's just that almost everything else in the system is more suspect than the ECM.
Since you can get your hands on one it wouldn't hurt to try it.
Do you have the under hood diagnostic panel ??
Have you tried to see if there are any trouble codes stored in it's memory??

 

I know the ECU seldom fails, but knowing that I was doing some ECU swapping a while back makes me think I might wanna check it just to make sure I've got a good one.

I use car-part.com sometimes to check interchageability of parts. If I need, let's just say, a fender for a 1990 something, and car-part lists that a yard has one from a '92, I assume that '90-'92 are the same.

I was checking for an ECU. They list a bunch of different ones for the N/A cars, and for the turbo cars they differentiate between the EGR cars and the non-EGR cars.

My '94 is an EGR car. The motor came out of a '95, non-EGR car. I swapped the intake and exhaust manifolds to keep the EGR. I don't know how much of a difference the EGR would make in terms of the ECU, but I suppose there's maybe enough of a difference that I couldn't really rule anything out by using the ECU from the car the motor came out of.

Yes, I have the under hood panel. No, I haven't checked for codes. Since the car has been sitting for 2 years, with no battery and no motor, I assumed there would be no code until the engine actually runs, and the computer starts getting signals from stuff. I would also assume that any codes I get now would be from 2+ years ago, when the car last ran. I know...I shouldn't assume.

I think I may have to go find a dealer with a '94 turbo, take it for a test drive, and throw my computer in it real quick to see if it still runs.

 

I took my ECU to the dealer and verified it's the correct one for the car. Still doesn't tell me if it's good, but I'll assume for the moment.


I seem to be getting a spark from the coil now, though I have no idea how or why. Maybe just bad connections where the ECU was plugged in, given that the car sat for 2 years? Who knows.


However, I can't seem to get a flash from my timing light when I connect it to any plug wire beyond the cap. The cap and rotor were new. I pulled them and put the old one back in...still nothing. Tried a different set of wires...nothing.

My guess is that it will just fire eventually, and I'll never know why. Probably bad connections or something, that just happen to get cleaned up by accident in the process of disconnecting stuff to check.

Frustrating, for sure...

 

I assumed there would be no code until the engine actually runs, and the computer starts getting signals from stuff. I would also assume that any codes I get now would be from 2+ years ago, when the car last ran. I know...I shouldn't assume.

Yup ... You should try pulling any codes, clear them, try to start it and pull them again.
If it's not starting I'll ASSUME that the computer would be able to ID the input it's missing. If you don't get a code you could always unplug the MAF or Cam sensor or whatever and see if it catches it. I think it will.
Might pinpoint the problem, might not be any code there but it's easy and you can do it right there at home.

Going through the different connectors checking for corrosion and reconnecting them might clear something up. Maybe you'll find some green fuzzy stuff inside one of them !
Have you tried to put a spark plug at the end of the coil wire to see if it's getting a good crisp spark? The inductive pickup will pick up an impulse that isn't hot enough to fire the engine. If you have an old plug laying around you should try opening the gap way up .060 / .070 and see if it will jump that.

 

I got my compression gauge back....165, almost exactly the same on all 5 cylinders (96k miles).

Opened a plug to .060, hooked it up to the coil wire, got a great spark.

Working on checking codes.

 

OK, to update....

I seem to have good spark to the cap, as verified by sticking a plug in the coil wire. I still have very little or no spark at the plugs, which are new. I've pulled them a couple times to clean them, and they're wet with fuel. The cap and rotor are new. The plug wires are a fairly new set of quality aftermarket wires, and I've tried replacing them with an older set of OE wires. Nothing.

I'm baffled.

I checked for codes. I got nothing at the A6 terminal (ignition), but I did get one code at the A2 terminal (fuel). The code was 335, which is "Request for MIL lighting from TCM"

Anybody know what that's supposed to mean?

 

I am still guessing timing is the culprit. If you have spark to the distributor, but nothing past there, the only cause would be either distributor, cap, rotor, leads or timing. Seeing as you have replaced the cap, rotor and leads, and you are getting hints of spark, it pretty much narrows it down to timing.

 

That's the part that baffles me. There's something really simple that I'm missing...it has to be. I checked the timing though, and it seems to be on the mark. I aligned the mark on the lower sprocket with the mark on the oil pump to get TDC, and this is where my cams ended up.




There's only one thing I can think of at this point. In the past I've done head gaskets on a couple 850's that I then had trouble getting running. In several cases I would crank and crank the car, literally for minutes continuously trying to start it.

I recall reading a few threads at the time from other people who had the same problem, and I don't recall anybody knowing why this happens. On the two cars I had trouble with, I just cranked and cranked and cranked, and eventually they fired. Once they did, I never had any trouble with them.

I'm assuming I'm at a similar point right now. My car sat for 2 years at least, the the car the motor came out of sat for about a year. It seems strange, but maybe that has something to do with it. I don't know.

On a slightly different subject...

I checked codes at the A1 terminal (transmission), just for kicks. I got code 223 (TPS sensor signal too low). I cleared the code, and verified a 111 code. I cranked the car again for a while, then checked for new codes. At the A1 terminal, I then got code 213 (TPS signal too high). I went from too low to too high. I swapped the TPS with one I have laying around, and once the battery is done charging I'll try again.

Finally, a funny story - I was checking this thread on my phone, and I got a pop-up ad that was obviously just using keywords. It said "Are you looking for Another dead Volvo?"

 

Nice to see another washingtonian on here. are the cams lining up with the v grove in the top timing belt cover? Technically there is NO distributor the rotor is attached to the end of the intake cam. At this point if your plugs are wet with fuel the thing is probably flooded. definitely check your cap and rotor for some build up. try sanding them down if there is buildup

 

yep, they're lined up with the groove. I don't know what happened to my pic in the post above.

I've pulled the plugs several times to clean them off. They keep getting fuel soaked.

The cap and rotor are new. I even cranked the motor with cap off to verify the rotor was turning. It was.

I'm totally baffled. The only thing I can think of is that maybe the spark isn't strong enough to jump from the rotor to the cap. However, it jumped the plug with a .060 gap when I had the plug on the cap end of the coil wire.

 

just for fun spray some starting fluid down the intake and see if itll fire i would spray it directly thru the throttle body. worth a shot.if you were closer id swing by sometime.

 

I've tried starting fluid. I sprayed it in just before the throttle body. It coughs a little, like it wants to fire, but just won't.

To add to the confusion, I noticed today that the spark is intermittent. I've been trying to crank it and check for spark by myself, which is a little tough. My arms are only so long....pliers in one hand, holding a wire, hugging the A-pillar while trying to reach the ignition switch in the car, know what I mean? Like yoga for mechanics.

Anyway, my brother came over today, and he cranked it while I checked spark. I used my plug with the .060 gap, and I get what seems like a pretty strong spark from the coil. However, it fires 4 or 5 times, then I get no spark for 3 or 4 seconds while it's cranking. Then it sparks a few more times, then nothing again, and keeps going like that while it's cranking.

I've also found that I'm getting spark at the plugs, but it seems weak, and obviously it's intermittent too.

This car is driving me insane.

 

Crazy idea, but are the plug wires hooked up in the correct firing order and also to the correct plug??

 

At this point, I'm a big fan of crazy ideas. Any ideas. Sadly, I've checked the plug order like 4 times.

I have another computer I'm going to check tomorrow. Currently I don't have a battery in the car, and I didn't feel like standing out in the rain to pull the one out of my V-dub.

If that doesn't solve the problem, I may push the car off a cliff.