91 chevy 1/2 ton. Idles and revs fine when in park, but it has trouble running when in gear. what's up?
runs great when not in gear, when in gear it dies at stops and bogs out a little when you get into the throttle. Has new injectors, tps, map sensor, fuel filter, rotor, cap, timing is right at 8 degrees. all vacuum lines good. This is a tbi injected 305. What wrong with this thing? Please help!!!
- 1 decade agoFavorite Answer
hey bud, i read what dodge man had to say and usually he doesnt stray to far from the problem, but...in this instance i would have to say before i started fudgin around with the timing chain or gears, i would start checking some very simple things. normally i would ask you if your check engine light was on but for some reason these older chevies sometimes dont throw the codes when there is a problem. your two main focuses now since you have already replaced the items mentioned above should be the egr valve and the catylitic converter. if your egr valve is stuck in a certain position your engine will idle fine most of the time depending on how bad it is stuck, but when it is in gear and under a load your engine will run almost like it has a bad spark plug, and you will have crap for power. also depending on the miles on the truck, assuming they are high based on the year you may want to consider a catylitic converter. they are usually recomended around 150,000 miles. when the cat gets saturated with hydrocarbons it increasingly cuts back your engines ability to rid of exhaust causing increased backpressure. in this case also it may idle fine but run rough when under a load. if that doesnt fix your problem, you may want to take heed to dodge man but i doubt thats the problem. on his behalf though i will tell you it is very hard to diagnose a car over the internet. lol you before you spend too much money just throwing parts at it you may want to consider atleast the diagnostic fee at your local garage. i hope this or someone else can help. godspeed
- dodge manLv 71 decade ago
i own a repair shop,and i,ll tell you whats happening to it,for one thing the timing chain and gears are probably worn out in it,and this makes the piston be out of time with the valves in it,as long as its not in a strain,it will idle good,but not in gear the computer is trying to make up for the difference in the timing,but it will only make up for 4 degrees of difference in it,you need to check the chain and gears,id say its about ready to jump timing from what you said about it,and also check your gas filter on it,it may be starving for fuel,but all Chevy's are well known for having weak timing chains in them,and this is whats causing a lot of this to happen,i average around 20 Chevy's a year or more just for timing chain and gears to be put in them,id check that along with a few other things on it,you can boost it on up at the distributor,and i guarantee you it will help it ,but it wont last very long until it starts to run bad again,try that though i think that will turn out to be the main cause of most of it,good luck,i hope this helps.Source(s): been a certified mechanic for 36 yrs.
- 1 decade ago
sounds like your timing might be a hair off, or there is a vacuum leak. Are you positive they are all good, I would check vacuum first, then got and loosen distributor bolt and adjust. A small turn means alot to that engine, so be careful.
Best of Luck!
- 1 decade ago
You didn't mention fuel pump. Sometimes this can cause this problem.
Check plugs too. I had a 94 bonneville that did the same thing. I replaced the plugs and it ran like new.
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- 1 decade ago
it either might be a bad clutch or you need to get your tranny rebuilt... take it to a transmission shop if you need to