‘85 600 turbo

So, the 600 suddenly is running terrible....apparently it has the ‘86 dizzy and computer with the G head (from what I’ve been told). With that said, this passed weekend I put the 804 injectors, head gasket, timing belt, 2.5” swingvalve and down pipe on it. Re-timed it and had it running well. Now the power is a bit lack luster right now, I’m still trying to figure out what exactly to do with the timing deal to make it right...none the less, I drove it home from my buddies house and it was fine (over an hour going down the interstate. Got it home and started messing with the timing a bit, I advanced it enough to where the power band was starting to come back to normal. Suddenly I fired it up later on that night and it developed a stumble, so I didn’t think much of it and drove it for about a mile, then it got worse so I just came home. Now it is running complexity abysmal. Engine is shaking, back fire out of exhaust, Doesn’t clear out at all through rpm range. I’ve checked spark from coil, to every plug individually, everything appears normal there. Fuel pressure holds steady at 48psi. Took a stethoscope to each injector and heard them all pulsing. 0 codes present in the computer, I even went as far as forcing the light to come on by disconnecting the air charge sensor, so I know it works and it pulled that code. I did unplug the o2 sensor and it did make the car run marginally better.....so my next plan is to check spark again tomorrow, get a real Stethoscope on the injectors and dizzy, and compression check. After all that is ruled out, next plan would be to just check timing again...maybe the belt jumped....if that all fails to Yield any result, I guess ohm check all the sensors....anyone have some different light to shed on this for me? The pictures I included are of the plugs left to right 1-4 and the pickup coil I noticed is a bit porous, but not where it actually picks up it seems....SDAC28 is becoming a distant dream at this point. https://uploads.tapatalk-cdn.com/201...671b91ebe.heichttps://uploads.tapatalk-cdn.com/201...e84b8bf6d0.png


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The 804 injectors will be a little large in your install, but not so much that it should cause big issues. The originals in that engine should be 27#, where the 804's are 35# injectors. I would think the ecu should adapt that much. But still something to consider. But that's like sticking +20's in your engine..

Have you actually done a kVa check on your spark? The tool is only a few bucks at your local parts store. How old are the wires, & rotor? They could be at fault. You can do a resistance check on the wires and see if you get any high readings. Also, are you running the original coil? I brought this up in another thread just a few minutes ago. Never really gave it much thought because I had never been bit by it, but my latest issue on my Scamp was a failing 35 year old coil... Swapped it out for a new Accell 8140M super stock coil, and all is right with the world again.

Not sure how much you've been reading on here, but a spare HEP(pick up coil) module is standard issue for these cars. Never leave home without one. Both my TM's have a spare in the glove box, along with a Phillips screw driver.. The OE parts were known to fail, and the aftermarket ones are even worse...

Looking at your pictures, it's obviously running rich. If you are down on power, you could very easily be off a tooth on your timing. Don't feel bad if you are, even the "pro's" get it wrong once in a while. Done it myself more than once....:p Go back and check all your timing marks again. From the picture, it looks like you have something going on in cylinder 2. Is that plug really wet looking, or is it just the picture? Almost looks like you are getting a little oil in that one...

Plugs should look like this if your combustion is right:

Attachment 62767

I was just using a old fashion spark checker with an incandescent filament. Spark was very true across all 4....definitely have considered a new coil and pickup just for good measure. I knew these injectors were a bit big for my app. But figured running a little Rich is better than not...Update to this story now, got home and checked compression on all4 cyls, right about 135-140 across all 4, so I’m super happy about that. Fired it up and accidentally had 1 and 2 wires crossed (oops) shut it back down, swapped them, fired it back up and pulled out the stethoscope, about 30 seconds into checking things, noticed it slowly sounding better and better and it finally ran right again. So up until this point the only thing I’ve actually changed back was my initial timing on my distributor. Everything else has just been checking and verification of other components. Could it be that, I had the timing so far advanced that the computer couldn’t compensate anymore and that after I had the battery disconnected overnight it cleared the computer memory and it finally fixed itself?...also I am fore sure checking my timing marks because the power is still quite poor as opposed to before I touched it (go figure). I read somewhere that advancing the cam gear one tooth boosts lower end power and fuel economy? (That article was based on an ‘88 if I’m not mistaken, so it may not be applicable to my ‘85). Thank you for the reply man. I appreciate it.


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You need to keep the timing properly set. One tooth on the cam is too much advance or retard.

Are you running a g head with a swirl cal? The pistons match the head at least, right?

Quote:

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Originally Posted by cordes

You need to keep the timing properly set. One tooth on the cam is too much advance or retard.

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Agree 100%. If it ran good before, and you are down on power now, money says your off a tooth, maybe two. Had the same issue with my Daytona after replacing the head gasket. It ran, but was obviously down on power. Thought I had it perfect, but after checking, the cam was off a tooth. makes a huge difference.

Seems that the intermediate gear and crank were off 1-2 teeth. Got it back together. Power band seems to be back for at least 1st gear, then when it shifts to 2nd it falls on its face and picks back up. So at least I have a direction to go here and my changes seem to be making a positive difference. Timing these things is really far more complicated than necessary. I really appreciate your guys input. If it wasn’t for the ghetto belt setup on these, it’d be way easier to mess with. But hell, 3 hours from tear down to test drive isn’t bad in my book. I’ll keep doing some reading to see if I can get it back to normal, but hell, apparently I didn’t look good enough taking it apart. So, I’ll just roll with the punches at this point. 👍🏻


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