hello friends i have a rebuilt 1988 305 tbi with long tube headers, 10.1 comp, flat top pistons, and puter compatible street performance cam. (idk specs on cam)
it will sputter and hesitate terribly on acceleration, even light acceleration. I accelerate very slowly not to get the problem. Check engine light is NOT coming on. It did this to me once the other night and drove fine yesterday and this morning. Got stuck in heavy traffic this evening and when I went to accelerate the problem occured and was present the entire drive home

i have had it run great for a week before and then it will hesitate when you take off or die and then be almost impossible to restart. Then the next day start right up and then you shift it into gear (auto) and it dies or almost dies. It burs rich and the it acts like it has no fuel when you start it so you have to floor it. runs great at high rpm, if you an get it there.

intermittent problems suck!

the only original part that i can think of is the throttle body and the spray of the injectors seems fine. Do you think it would need a chip for the computer? some one said that maybe the o2 sensors dont get hot enough with long tube headers but i dont know what the symptoms of that are. valves also clack at high rpm sometime no matter where the timing is. anything is helpful

 

main question. will a chip fix my truck?

i have gone threw everything i can think of.

 

have u tried to reset the valves/rockers?

 

craby i like you, your the only one that try's to brainstorm with me.

by reset do you mean adjust? when we rebuilt the motor we adjusted them. the motor has maybe 2k on it just to let you know. I could redo them but i dont think that explains it running the way it does. right?

only under a load do they clack.

 

your right if they were to tight it should do it all the time. is there a chip on the key? well it would be better if it did it all the time. easier to find. check the spark volts when its running good and bad. also check the timing in both cases. need to try and isolate the problem to one, fuel or spark.

 

now the problem is all the time but who knows how long it will last.

thanks, thats what we have been trying to do(isolate fuel or spark) but both are fine and as far as components we have been replacing possible culprits. no chip on key, its a 88. The timing is not spot on but its close cuz we have an upgraded cam.

1.spark is good
2.runs rich so plenty of fuel while running
3.new fuel pump installed made no diff last month
4.new regulator done last week


this is y we can only think its the computer screwing up the air to fuel ratio but thats been replaced too and made no diff. Maybe a performance chip could read broader band of variables and correct the air to fuel. what do you think?

could air to fuel cause the problems in the original post?

 

clean the maf and 02 sensors? u should pick up a dealer service/shop manual for your yr and model. its either a bad sensor/part or connection somewhere. it may be less expensive to take it to a shop and have them test it. u r going to have to find out what volts should be coming out of the different sesors and ignition parts on the car, then buy the test equipment and either cut and repair wires to test or buy the plug in test setups. if u are getting good pressure to the tb then if its fuel it would have to be electrical or in the tb injectors.

 

no MAF on these setups.


hows your fuel pressure? new pump dosent mean 100% that its going to have good pressure. Almost sounds like a clogged fuel filter to me..

as for the valves clattering.. hows your oil pressure? I have heard of people running high volume pumps actually pulling the oil out of their crankcase/oil pan if its not bigger than stock. i would assume it would pool up in the valve train.. but it may all be in the valley, away from important parts like rockers..

 

You really should check for any error codes. Your system could have some stored, even though the light isn't on now. Do a search here, there is a thread on how to check codes. Or search online.
First of all, your TBI engine doesn't have a MAF sensor, so don't bother trying to find it.
If you look at it logically, your engine appears to run Ok until it warms up. It would make sense to suspect one of your sensors.
Are you still running with the stock air cleaner? Mounted to the base of it is a Manifold Air Temperature (MAT) sensor. It looks like a round probe, about 1/2"-3/4" in dia. The MAT sensor reads the incoming air temperature, and sends a signal to the ECM which will then control the EGR valve. An EGR valve that goes haywire will make the engine run crappy. If that sensor is dirty, unplugged, missing, or bad, it could be your problem. If it's bad, you should have an error code 23 or 25.
You also have a Manifold Absolute Pressure (MAP) sensor. It is on a bracket mounted either to the firewall on the drivers side near the outer corner, or on the passenger side cowl. The MAP sensor monitors engine load and vehicle speed, and sends a signal to the ECM to control air/fuel delivery and ignition timing. If that's bad, you should have a code 33 or 34.
Another thing to look at is your engine coolant temperature sensor (not the one for your gauge). It's either on your water neck/stat housing, but more likely on the front of the intake manifold, with two wires (black & yellow?) going to it. When the engine is cold, the engine management system is in an "open loop" mode, and air/fuel is supplied by a fixed setting in the ECM. AFter the engine warms up, the system goes into "closed loop" and some of your sensors now control the air/fuel mix. If the temp sensor is bad, you should have a code 14 or 15.

 

thanks for the list of things to look at. i will get on it. If i ever seem unclear on my symptoms its because the problem changes often or just goes away for a week. This is my brothers truck and we have been screwing with this off and on for like 6 months but i want it to be reliable for him because he is the one that spent 2 summers in florida building that truck(crazy humid). He now hates the truck.haha