hi everyone! I just got a new tranny put back in her so shes back to life but now there is a new problem... every once in a while or few minutes the truck runs terrible like its sputtering... then it stops sputtering and runs perfect... then it repeats again and again... what does this sound like?

1988 5.8efi with a new C6...

oh just to tell you guys I have the heater core out so I have the one hose pulled out and just have one there so I can drive it... and the flow direction is right....
I dont know if this is the problem or not..

 

clogged fuel filter maybe?
Tim

 

can't be it was juts replaced this summer

 

it was just a thought(though not a very good one)
Tim
EDIT: you might be best off by taking it to a shop and let them check all your sensors....i had exactly the same problem on my b2. i never fixed it, i sold it instead.

 

I have the same Bronco right down to the color but with the little 5.0. Had the same thing happen once. Real bad shudder and sputter. Drygas, a new fuel filter and an injector cleaning cleared it right up. Hasn't happened since. I also replaced the gas tank too since it rusted thru between the skid plate...I think I was getting moisture/ice in thru there.

 

update: I had the idle bypass valve checked, I think thats what its called but anyways... the vavle is still good... any other ideas? steve could ya help me out a bit? please?

I have no money to have a mechanic look at it so you guys are my very best bet....
thanks in advancea


injector cleaning--- how do I do this?

oh yeah.. i'm not too sure about drygas either...

 

My 88 has the 5.8L as well. Check for vacuum leaks. At the top of the motor there is the intake manifold with a some vacuum hoses going to various places, such as the EGR, power brake booseter, cruise control and interior controls. If you pull a hose, it will run rough until you plug the hole, say with your finger. If you don't have a vacuum gauge, then just check each each hose to see if it runs better when you plug with your finger vs the control. I found a leak in the cruise control and the interior vacuum controlled items. There are several fuel injector cleaners you can buy at the auto store that you pour into the gas tank.

 

ok, i had a BII at one time, and it had the 2.9L and it would run great 98% of the time. However, after I had done lots of stuff to it, i could not get rid of one problem for the longest time. If it were to sit for about a half hour to about 2 hours after being shut off HOT, and then restarted, it would start to sputter and surge really bad about a minute after restart, and it would do that for a minute or so maybe and stop. It wouldn't do it all the time, and sometimes it would do it just after extended periods of idling, it would sputter, surge, and then stall, if it didn't stall, somethin would click and it would clear up and be fine. Anyway, if that's what you got, then i suggest an O2 sensor, in this case, i finally decided i was gonna check the wiring for the O2, and i touched the wiring and the top of the sensor broke right off, and i left it disconnected, and it ran exactly the same! it didn't throw a check engine light until after i drove about 50 miles. I put in the new O2, and it never did it after that. just my $.02, might be worth checking out that wiring, cuz after all, you did pull the tranny out, and the O2 and it's wiring are down there, and either could've been damaged, since the problem started after tranny replacement right?

 

I will check everything out, thanks for all your help and if the O2 sensor is the problem thanks...

and yes the problem started once the new tranny was put in...

 

I just unplugged the O2 sensor and it did the same thing... but I dont know why my "check engine" light didn't come on... does it have to throw a code to be faulty?

 

same deal when i did it, and it DID not throw a light even after it was unplugged, and it ran the same, those early systems rarely caught problems as efficiently as they do now. i would definitely go for the O2 if it runs the same after you unplugged it. MAKE SURE you check the wiring for the O2 as well, kinks, chaffing, etc...

hope it fixes it! let me know if it does

Gary

 

You may also want to check your spark plug cables....especially where the EGR stove pipe runs up towards the intake....wires can hit it and insulation burns off causing cross arcing .....this will definitely cause a nasty sputter...

I good way to check for vacuum leaks is to get a propane bottle with a nozze and hose over it and run some gas around the intake, vacuum hoses, etc....if the idle speeds up then you have a leak in close proximity.

you may also want to pull the codes to see if there is any component that has failed....the OBD system is a great tool...

 

You may also want to check your spark plug cables....especially where the EGR stove pipe runs up towards the intake....wires can hit it and insulation burns off causing cross arcing .....this will definitely cause a nasty sputter...

I good way to check for vacuum leaks is to get a propane bottle with a nozze and hose over it and run some gas around the intake, vacuum hoses, etc....if the idle speeds up then you have a leak in close proximity.

you may also want to pull the codes to see if there is any component that has failed....the OCD system is a great tool...