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Timing issues

Littlered89

Littlered89

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Hey all, I need help. I have a 1989 dodge d100 3.9. The thing ran so good before. It never didn't start, never left me stranded. It was a great little truck. I recently pulled the motor and trans to regasket and clean everything. New oil pump and timing chain while it was apart. Now I can't get the timing adjusted. I start it and it sounds like a Harley until the computer figures out what it's doing then it smooths out. I've don't the whole "unplug the temp sensor" deal several times. 10° advance like the book and hood sticker say and that's not right. Then when I plug in the temp sensor it gives me more advance. What am I doing wrong or did dodge not use 10°? I just want to drive my truck again. It's fun and was such a good truck. Please, any help is appreciated greatly.
 
I'd be looking at what you DID to the truck. It ran fine before, it runs poorly after. That points directly at what you did to it.

From your post, I'd suspect that timing chain work and would start there.
 
I am in full agreement with that. That is the same advice i give people when they ask me for help.

I brought the #1 to TDC on the compression stroke, pulled the chain cover and distributor cap. Both dots were up and rotor was pointing at the oil pressure sensor. I put the new chain and gears on the same way the old came off because that's how it was running. Then removed the distributor from the block and did not touch the rotation of the engine until the distributor was back in and pointing to the oil pressure sensor again. After that I could do the torque converter bolts. The only modifications I did in this project was I removed the heat riser from the right side exhaust manifold and I removed the EGR valve with a block off plate and new gasket. I used a torque wrench on EVERYTHING as to eliminate any question in my mind of that being a problem.

I've done this project several times on carburetored engines but never on a late 80s fuel injected engine. I'm not perfect and I'll never claim to be but this is as "by the book" as I know. If there is something I missed please help me figure it out because I am at a loss. I feel like it's some stupid computer thing that is off the wall and no book will tell it. I don't know. Thanks again.
 
Don't you just love a computer controlled anything? (Not)

So, just by chance, could the computer be seeing a "colder engine" than before since you removed the heat riser and the EGR? Maybe that temp sensor is bad or there is another one somewhere that causes an extra cold reading to the computer? Just tossing ideas, I'm not familiar with that engine and I hate computers.
 
I suppose it's possible. I'll have to go through the book to see if there is more then one sensor. The one that I know of is new. I didn't see another one while the motor was out. Computers suck but the truck was $500 6 years ago and ran so friggin good.
 
Of course you know that having a "new" temp sensor doesn't mean its a "good" temp sensor. What was the problem with the old one?
 
I understand that, I have bought bad ones. The old one I took out and put in an aftermarket sensor for and aftermarket 3 Guage cluster. BRAIN FART. Once I realized the mistake I made there, the old one was long gone. I'll look up how to test them. I did notice the factory Guage don't move when I was able to drive it recently. I'm used to carburetored engines.
 
Littlered89 said:
I'm used to carburetored engines.
Click to expand...
Me too.

As for the original temp sensor, it most likely is a temperature dependant resistor. In other words, the resistance measured to ground changes as the engine temp increases.

Can't tell you if the original style will work with your aftermarket gauge cluster or not. But I'll bet the original computer wants to talk to an original type temp sensor.
 
It absolutely does. When I had the after market "thermometer " in place of the original sensor it would run great from a cold start but after it got warmed up it didn't want to start. I put a new original type sensor in and that solved everything. Now I have this BS I'm trying to figure out.
 
It was, I corrected it. Both dots are straight up and rotor is pointing at the oil pressure sensor.
 
Make sure ALL the ground straps are good & connected, bad grounds will cause problems. (ECU to body, engine to body, body to frame, engine to frame) NTK, same company that makes NGK spark plugs, make good stuff. I used their sensors on my 95 Dakota with good luck. (Rock Auto carries them.)
 
I'll check for grounds again. I'm pretty certain they are all hooked up. I noticed when I plug the temp sensor back in the advance changes. Am I supposed to set 10° with it unplugged and let it give me more advance or am I supposed to compensate so I have a total of 10° after I plug it back in?
 
I would think the 10deg. should be set with the sensor UNPLUGGED, but it should have the timing procedure under hood somewhere, I think.
 
All it says is 10°. And to "follow procedure in manaul" I don't have Said manual. I do have a Haynes manual and I followed what that said but Haynes manuals only get you so far.
 
Yeah, Haynes manuals aren't very good. I'm pretty sure it's means, to unplug the CTS, set timing to 10deg BTDC, lock the dist. down, shut the truck off & reattach the CTS sensor & you should be set to go.
 
That's what I did several times to make sure I didn't make a mistake. The last time I had it running it idled like a Harley and started to smoke through the air cleaner so I shut it off and slammed the hood.
 
You might have to put everything back the way it was to regain that well running truck you no longer have. Or delete the computor all together and buy a non-computor carb. You can't simple unhook things from the computor without making it think things are lets say hunky-dorry.
Not sure when the computor got smart enough to put timing where it was supposed to be reguardless where you set it. I know I tried it on the 93 and it would reset to where it was supposed to be if that make any since. Computor told the coil when it was to fire and not the distributor position. Both should be HEI.
 
I haven't really changed anything as far as the computer goes. Just the egr valve but that's just vaccume. When I could get it to start and run, it wound run bad until the computer figured out what it was doing and then it would smooth out. But it seemed to have a bit of a misfire. I could hear a random odd noise though the tail pipe like a misfire. I can put the egr back on and see but I don't THINK that's it. Maybe thought. Kind of at a point where I'm willing to try anything.
 
Because it is TBI, (I had a new 90 D150) the computer adjusts the timing for best performance, the pick-up coil/cam sensor under the distributor cap & crank sensor, tell the computer when to fire the TBI depending on where they are on the engine cycle. Very similar to Magnum engines with MPFI. Sometimes it takes the computer a few minutes to re-learn things if it has sat for any length of time with battery power disconnected. Can you let the truck idle a few minutes after you start it, without any issues? If you can, try that, then, take it down the road easy & see if it clears up.
 
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