10% compression in #1 question

rlpjw1959

rlpjw1959

New member
1989 3.0 171K miles. I have a rough idle problem, and is worse when the car is warmed up. ( boarder line stalling) I've checked for codes and there aren't none. There is no check engine light. I've had 3.0 in the past and the truck seems to run fine.

The guy tells me there is only 10% compression in #1 cyl. And have to rebuild the engine. I don't know I believe this ( or just don't want to)

1. If this is true would I have a check engine light?
2. And would I notice a "significant" slower 3.0 :)

I looked at the plug and it looks like all the others... Can I get some thoughts from some from some experts!

Thanks!
 
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Yes I think I'm going to do that...

But regarding the check engine light and overall operation of the truck driving. What would be your thoughts on that.
 
rlpjw1959 said:
Yes I think I'm going to do that...

But regarding the check engine light and overall operation of the truck driving. What would be your thoughts on that.
Click to expand...

I don't think bad compression would cause a check engine light, no, and a blown cylinder would definitely cause an engine to run poorer.
 
My trucks been knocking for 6 months and has not thrown a code due to it. I have another motor ready to go but waiting for this one to blow.
 
most pre OBDII wont have misfire monitors. so yours wont throw a cel. should do your own compression test to make sure
 
I recently had the same problem in my 3.0. It was low compression on #2 cylinder. I changed just about everything and the last thing I changed that fixed it happened to be a bad injector. The compression went straight back up and ran fine after that.
 
A bad injector has nothing to do with compression. Are you sure you didn't have a mis on #2? A bad injector will cause a mis but not low compression.
 
Pitbull - no other problems... Does not burn oil, coolant stays good, truck does not overheat... No white smoke frm exhaust.


I'm going to do a compression check myself when I get home. (guy at work let me borrow his) If I get good compression I may look at the injector as the issue... But let's see what happens.
 
Cylinder #1 has 95 lbs compression. Messured it several times... There is a miss somewhere or something going on that is causing the idle problem... I've gone over all the vacum hoses they seem fine. I changed plugs, cables, distrubutor.

Fuel injector? Is there a test I can do...?

Thanks everyone for all the suggestions...
 
Unfortunately There is no way to check except to change the injector. PittbullRescuer alls I know is that i did a compression test and #2 come up short on compression and the injector was shot and when I replaced it it brought the compression back somehow. I know it dont make since but it did work for me somehow. and as far as a (bad exhaust valve) That would definently make since. They are known for such things more so then the injector deal but alls I can say is start with the cheaper one and work your way up. Sorry for the luck
 
OP, unfortunately since it's OBDI, there's no way to tell which, if any, injector went bad. On newer ones you just move them around and see where the code goes. If the code follows the injector to another cylinder, you know it's a bad injector.

Not sure what your budget is but my advice, send your injectors out to WitchHunter for a clean and rebuild, they could probably use it anyway. If you really want to get into it, pull the heads, do the problematic head gaskets and send the heads to a machine shop for a quick rebuild. You'll spend a few bucks but it'll love you back for a long time to come.
 
Or, if you're not too far from PA, sell it to me! :) I've wanted a 1st Gen for a long time and I need a winter project to keep me out of trouble.
 
Haha, all good. There's no 1st Gen's that clean out here.

If you're in it for the long haul, do the whole top end rebuild idea. It's well worth it. Good luck.
 
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