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horrible problem after timing belt change

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wolf alchemy

Proven Member
724
14
Mar 4, 2014
kouts, Indiana
1990 Plymouth laser RS turbo. so I got my timing belt done a long time ago and not even 5 miles away the car starts jolting back and forth, I pulled over and killed the engine. rotated the cams and they looked lined up. car was fine after that oddly. though now it randomly drops 1000-1500 rpms during constant speed cruise. acceleration unaffected. took it to a guy whom sorta checked other tick marks. he said they were lined up fine. started car today after a month or two of sitting and the problem has gotten worse. now according to 1glink my timing is dropping by 4. so if its at 21 it drops to 17 and jumps back up. so pretty much back and forth multiple times. before this the car couldn't idle without dying. also decided to run test on 1glink even though theres no engine light and it said "serial com error" help as soon as possible would be appreciated. buying a wideband to help narrow down if the problem is fuel or air.
 
Any idea what else was touched when the timing belt was done ? Could it be something really dumb like a couple of the plug wires aren't in the right spots ?
 
I pulled all plugs to look at them so no. a town shop did it for 800. they looked to have burn marks on the sides and white corrosive bubbles on the arm of the spark plug. the curvy thing. any idea what that means?....the burns and corrosive. I can get a pic if you like
 
no. its wired correctly. what Im saying is. (4=#1)-(3=#2)-(2=#3)-(1#4) my guess is he was scared of putting a plug back in the wrong spot so he numbered them with a sharpy before removing them. but I guess it could be a problem if they unplugged the from the distributer. but how would that make my timing be haywire or cause one random 1000-1500 rpm drop middrive? it wouldn't. itd be a constant problem so I'm 83% spark plug wires are not problem. ignore bad grammar. key board is dying, or I have a bad virus.
 
OK so they're not wrong at the plugs OR at the coil pack, as long as 1/4 are together and 2/3 are together, timing marks are lined up, maybe a loose fuel injector connector ? Unplug all 4 of those and plug them back in, just to be sure. It just sounds electrical, and not mechanical, if everything is lined up like you noted.
 
The guy who checked it didn't remove anything, he just looked down the side of the engine. I'll try the injectors now. And ideas on what a serial com error is?
 
One possibility is the harmonic balancer spun. It is common with our cars and their age.
 
Yes and the timing mark is on the balancer. So if it spun just a little bit, your timing is off even though the mark lines up. The balancer is just a metal hub with a ring of rubber and the outer balance ring press fit over the rubber. When the rubber ages it deteriorates or shrinks and allows for that outer ring with the timing mark to move. So when you you set your timing it's off.

It actually makes sense because it will spin in a retarded direction which is what you said in the original post. And if it has progressively gotten worse which these do you will get to a point where the car won't even start.

At the very least it's one thing to check. I am assuming you did not change anything else like plug fire order etc. so it's got to be something that is progressively changing. Plug order is either right or wrong.
 
Serial com error is your computer (laptop) telling you it doesn't recognize the port you are plugging into for data. Try a different port or configure that port.
 
Yes and the timing mark is on the balancer. So if it spun just a little bit, your timing is off even though the mark lines up
The balancer is not even on the motor when you set timing it has nothing to do with mechanical timing. If the balancer separated the marks on it wouldn't line up with the cover and it may look off if you checked with a timing light but it wouldn't actually affect the timing belt. If the balancer was separated it would just affect you accessory belts and your alternator, water pump , ps, ac.
 
Wrong. Why would the balancer NOT be on the motor when setting timing? The mark is on the balancer to line up with the lower case mark for TDC static timing with cams as well as advanced timing since he has a 1G with adjustable CAS. So if he had his timing belt done before it's started to spin and is now off timing, he and the computer are trying to compensate. I never said it was the smoking gun to his problem but makes sense since the issue has become progressive. Please read the entire length of post and refrain from being combative to people who are trying to help.
 
I think he meant mechanical timing. Do not check tdc with the harmonic balancer. At the very very least check it mechanically with the number one piston or take the timing covers off.
 
Which would have been my next suggestion to hence verify said balancer of spinning or not before I was so rudely jumped on. Not a bad idea to double check the CAS either. Any who my main point to all this was that the big clue here was the problem got progressively worse. So we have to look for something that is going to do that. I just get frustrated when people are ligitimately trying to help and get attitude from the very people who are supposed to be "Wiser" than the rest of us. You would think I told the guy to check his tire pressure and put NOS energy drink in the gas tank.
 
Yupok you seem to be suggesting timing will change if the balancer slips. It will not. Only thing that could happen with a slipping balancer concerning timing is you could not properly set or check base ignition timing. Mechanical timing isnt affected at all
 
The balancer is not even on the motor when you set timing it has nothing to do with mechanical timing. If the balancer separated the marks on it wouldn't line up with the cover and it may look off if you checked with a timing light but it wouldn't actually affect the timing belt. If the balancer was separated it would just affect you accessory belts and your alternator, water pump , ps, ac.

Yupok you seem to be suggesting timing will change if the balancer slips. It will not. Only thing that could happen with a slipping balancer concerning timing is you could not properly set or check base ignition timing. Mechanical timing isnt affected at all

This is all accurate information whether stated as someone put "rude" or coated in sugar....
 
I'm suggesting that if the guy(s) at the shop(s) he brought the car to, to check out the problem tried to check/adjust timing with a possible slipping balancer they only made the problem worse. Again, it was just one thing to check. The way I understood the post was that a shop tried to adjust timing.

SO does anyone else have any good ideas? I would check/verify timing to make sure the balancer is ok and that mechanical timing is good. Then verify the CAS timing. If they are good, then you ruled that out. Again with the age of our cars and this being a progressive problem, I would rule out mechanical failure first before electrical failure. THe car runs, like crow but it runs so it's a game of process of elimination now. Otherwise someone would have hit the nail on the head with this already.
 
This might explain what's going on though I'm not sure since my gauges work fine, but I believe that about the same time the car started acting up my amp died, so I'm gonna try unplugging the battery for 5 secs then unplug my o2 sensor to see if the cel light will come on. If it doesn't that possibly means fryied ecu. Thankfully I have a second ecu. My gf said to take it to Dodge. Since I know nothing about timing or cam gears, or the camshaft position sensor. Do you guys think taking it...well if ecu swap fails I'll definitely tow it there. But do you guys think Dodge will be able to help? And lastly sorry for late responce. Been working and driving a V6 5-speed mustang, so being without my car isn't so bad. Exspecially since I've been drifting. Love snow.
 
possible reason behind fried ecu. when hooking up battery interior fuse blows. if I hve to hook up the battery a specific way, let me know, and if its not too much trouble. what wire gives the ecu power so I can give it its own fuse before ecu(recommended voltage), and what/where are the grounding wires that might be causing my fuse to blow. not too good with electrical. I can only souder and connect wires well. yes I understand the basic principle of a car wiring system. but only the basics.
 
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