What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Bad stumble from 1800 rpms on up?!

Sorry, the exhaust sysstem is new about 5k. It has dual exhaust with 2 cats. It was running fine up until about a week ago.
 
Leper said:
sounds like egr to me. Could be a coil breaking down.
Click to expand...

I'd pull the EGR vacuum line and plug it (from the intake to the EGR solenoid or to the EGR valve itself) and take it for a drive, see if it goes away. Your problem sounds consistent enough that you should know right away if thats the problem.

Sounds like TPS is out of the picture (you can still test if you like, it never hurts to eliminate components that may contribute to an issue) since there is no problem at idle. Testing the coil won't hurt either if you plan on checking TPS. I know the TPS testing procedure is over on thirdgen.org, not sure where the coil procedure is, but I'm sure its been typed up before as well. :)

It also sounds like ignition should be at least put further back in line since the RPM issue is under load ONLY.

Fuel maybe, but with a specific RPM range and continued acceleration, I'd tend to lean away from that right now.

Taking a guess, but your EGR valve may not be operating correctly.

Coolant temp should make no difference, it should be an across the board issue if it were reading too hot or too cold.
 
Last edited:
You say you checked the plugs and wires, but what about the cap, rotor, coil and pickup? It sounds like an ignition problem to me.
 
sorry i didn't answer any sooner but i use the factory distributer in my 88. i don't like accel and i can't afford malory so i just get the distributor from a local parts house like o'reilly's that handle quality reman stuff and get a life time warranty. i know a lot of people will disagree with me but the only thing the after market distributors are good for is a little mor rpm range and not much of that and if you are pushing alot of fuel to the motor and need to burn it. but what you are discribing is exactly how mine was acting.
 
im a little late on this tread but my little jeep was ding the same thing it once i got above 1800rpms it would just bog down i checked everything plugs wires cap rotor new fuel filter and couldnt find anything wrong. took it to get it checked and the cat was bad the exhaust couldnt get out cause cat was cloged up so it after 1800rpms it wouldnt want to go. take it to a shop and they should beable to check it for free like they did mine. i bet u $20 bucks uyour cats went bad.
 
Yes, the distributor could be trash, there have been a fair number of psots lately about people having problems with their distributors.

Still seems a bit odd that it happens ONLY under load, and there is no other symptom of this problem (at least that has been mentioned) if it's ignition. But still not ruling that out...testing those components won't hurt, just a bit involved.

Would be odd that two brand new cats would go bad (even one would cause a problem) but with tapping the exhaust and measuring backpressure unless they are easily removed and inspected, they are a bit difficult to test.
 
You can *kind of* test the cats using a vacuum gauge on the intake manifold. Of course as you rev the engine the vacuum will drop. When you close the throttle again, the vacuum should go right back to where it was initially. If the vacuum stays low, that suggests a plugged exhaust.

It's not as conclusive as measuring pressure directly, but it is much easier to do.
 
if it starts cutting out on you trying ot go faster above 1500 or so RPm then i would really suspect fuel delivery issue

sounds like you are TBI, but i never have had a TBI daily drive,r but ill say this anyways:

had this happen to me many times and it always ended up being a badly curved hose at the fuel pump, or carb or somewhere else


also does yours ever have any hard time starting up ? take any extra cranking to start it up, cold or hot ?

if there is then i would highly suspect old worn fuel pump

happens all the time, common problem on these TBI rigs




good luck
 
Thanks for the insight and I will look at the hoses at the fuel pump. The pump however is new and ran fine for a few thousand miles before this happened. Thanks for all the help here guys I am gonna drop in a new distributor (from another truck that I have) and see if that helps. Thanks again. You guys are great.
 
If the distruputor dont fix it have u tried advancing the timing. I remeber when i changed intakes I had the timinn off and it would run good until about 1500rpms then the advance on it would get of and i just had to turn it counter clockwise until it stoped and ran good and it fixed it.

Also on the cats the one when the one on my jeep went out i only had 10,000 miles on it and it went out. I was told it went out from the engine running a little to rich. I just took my to a mechanic and he checked it for free all he did was check the heat. The way he checked was by temp he measure the temp reading there it waz running like 800 degrees in front of the cat and like 200 behind.

If you still cant find anything wrong with it call a couple local auto shops and see if they do free inspections. I know most of the place around here do. heck one time it took them 5 hours to find out what was wrong with one of my cars and didnt charge me but i gave them $30 since they went through all the trouble.
 
That's a good point. An infrared thermometer can be used to check cats. They are supposed to be hotter on the outlet than the inlet.
 
Hey guys, sorry I havent been on lately, had a little accident on my bike. I didnt change out the distributor and the reason is because the truck runs beautifully in closed loop mode. i figured that it wouldnt be a dist. prob if it only happened when it was warm. If anyone has any info to contradict that please tell me. However since I figured it was a sensor problem I replaced the o2 sensor but it didnt help. i also checked the cats with a temp sensor and they seemed to be operating just fine. I also played with the timing a bit but it was a give and take at high and low rpms and didnt get rid of the problem. Any other ideas before i replace the motor and use it as an anchor for my boat! Thanks
 
coolant temp sensor on the intake????????
that would cause the engine to think it was cold even at operationg temp. this would cause the computer not to alow for the right timing advance. i think. like i said in my previous post, " i am no expert". i have found very few people who realy know very much about fuel injection, most are full of bull crap and want to think they know something about it.
 
true true. yeah i guess I should go get a temp sensor and see how that goes. Also the truck threw a code yesterday so I going to check it now. Thanks again.
 
You must log in or register to reply here.

Latest Posts

Top Bottom