so i have exhaust on my 87 t2 and the boost comes on good then stays boosting but hesitates and bucks and feels like a fuel cut and many others say so too, but hook one up and no difference hmm.... lets see i have just put new secondaries and walboro 255 and fuel filter and just changed the oil today if thats relavent and new plugs new ground on the bell housing to firewall

things i havent done yet..:
1. rewire fuel pump
2. test afm
3. test tps
4. well it idles fine but i havent tested for vacuum leak underthe manifold
5. ??

i dont know what to check next besides my list...

im sending an s.o.s. for help

 

bump

 

There are no bumps allowed in the technical sections.

Set your timing, TPS, etc..

And rewiring the fuel pump never hurts.

Around what RPM is this happening?

 

3500 + i know im just impatiant so i have to keep putting it at the top so peeps can see it

 

Did you port your wastegate when you put on the exhaust? How do you control your fuel pressure? The re-wire and grounding is what took out most of my problem, but mine was from the start and not only when I added my 3in TID. I dont have an after market exhaust yet.

 

nope and im not controlling fuel pressure .... suggestions for fuel management

 

get a boost gauge and post up some numbers.

if your spark plug wires are getting fairly old then replace them, changing the spark plugs never hurts either.

 

they are new plugs like two days old new and i have a boost gauge and it reads 5 lbs then its like when the turbo starts to really suck in air like during the efficiency area of the turbo it cuts out like the is a air leak or fuel cut and it drives perfectly fine out of boost ? could my turbo be bad? or my wastegate?

 

I've said it before, and I'll say it again. Ground wires. Just replace them, and it'll probably take care of it. Bad grounds cause hesitation from 3500-4000 RPMs. It feels like fuel cut, but it's the grounds.

 

you didn't mention spark plug wires. pull them off and check the contacts and just general all around condition of the wires.

 

if its hitting a wall between 3500 and 4k it sounds like a secondary injector issue. E.g. disconnected injector.

 

could be the secondary injector clips, the OEM injector terminal clips tend to break with age and the wires push back into the connector so there is no connection at the injector, that is something to think about but you would never get much higher than 5K RPMs even at light throttle with only 3 injectors firing.

 

Remember, light throttle applications generally remain in 2 injector operation.

 

well where are the other grounds i changed the bellhousing to fire wall and added one to the battery could it be my ecu? some of the electrical areas on my car seems like moisture might have got into them like my engine fuse box but i changed those out alreaddy, would it help to add a ground on each coil pack bracket? even though i heard someone once say "dont just add grounds everywhere just replace the factory grounds with new clean ones" and like i said earlier i just put new secondairies in and the clips where fine but i didnt check to see about the wires being pushed back ill check that out today and see

thx for input guys i post again with results

 

?

 

so i finally put a wide band on my car and under light load to boost goes way lean like 17.5-19's afr but idles fine and low rpm driving is fine. i just put new map sensor on and no difference and also got the new injector clips but havent put them in yet. and awaiting my new tps, plus i have the fcd on my car now to so thats not it

 

holy **** 19 afr!!!!!!!! you're engine is going to EXPLODE. are you keeping track of boost when this 'fuel cut' hits? if its not hitting at 8psi every time, its something else so take the FCD off. you're already pushing it as is, theres no need to boost even higher than 8 and blow your engine.

 

well i dont let let it boost because it will do it under load even not in boost. but its only boosting 5 or less pounds and it does absolutly nothing under boost or load so.... i dont even know how to describe it.... but as if the motor turns off then comes back on and crackles/backfire alittle

left to do.
1. ecu grounds
2. change ecu
3. rewire inj. pigtails
4. afm?
5. tps (new one not installed)
6. any other ideas????

 

Like JRAT said, one or more of your secondary injectors is not coming on line. Why? Go t me. You have to take a look with eyeballs and or a meter.

 

so finally took notes on my cars symptoms

according to my boost gauge as follows:
at 15# vac.-rich
at 10# vac.-stoich-lean
at >9# vac. very lean/cut out

10% throttle @ 3k rpm cuts out if vac. is less than 10#

3K rpm max @ 10#vac

ideas needed badly and i can elaborate more specifically if dont understand my lingo...

 

no ideas anyone.....

 

well back to the drawing board
i just put a different afm on and no changes

how do u check an injector with noide light?
and why hasnt anyone came up with a new intake manifold for the fc3s since most people run with out emission and have block off plates so why not make a indvidual pipe for each intake port and join them at the throttlebody?

any one in the nashville area want to make some extra money helping me out because im about to drive it off a cliff.....

 

so finally took notes on my cars symptoms

according to my boost gauge as follows:
at 15 in. merc. vac.-rich
at 10 in. merc. vac.-stoich-lean
at >9 in. merc. vac. very lean/cut out

10% throttle @ 3k rpm cuts out if vac. is less than 10 in. merc.

3K rpm max @ 10 in. merc.vac

ideas needed badly and i can elaborate more specifically if dont understand my lingo...

sorry about that i had the pound sign posted instead of inches mercury

 

well ?
where can you get a new fuel pressure regulator and any one i should get and or not get?

 

someone has got to know something and my offer still stands for paid help in middle tenn.