marine tech needs some auto tech help

**fkboatman** · 10-08-2008, 11:09 PM

I have my 91 tbi v-8 5spd camaro acting stupid (again) Do we have a auto tech in the house or a savy helper on the related issue

**boilerdawg** · 10-09-2008, 06:28 AM

i have a 90 iroc with the 350 tpi. not an expert but maybe me or others can help ya with some more details???

**hydrostream1** · 10-09-2008, 06:38 PM

I might be able to help you,I know the TBI setup well,its a good system,hardly any problems

**alwayssomethin** · 10-09-2008, 07:25 PM

what is it doing

**fkboatman** · 10-09-2008, 08:28 PM

Have no codes, fuel pressure is 12.5, new injectors, coolant temp sensor, tps, map, sensor, knock sensor doimg it thing, new 02, new module, new pick up coil. start car in morning,searches for a idle, have to feather clutch and gas to get out of driveway, car has a ruff or light studder at 2500 rpms in 2nd gear only. engine will not take load from clutch well at all. when its warm has a light miss. all the time. I put all new mentioned above ac delco parts down to cap, rotor, wires plugs, new fuel filter. compression test great, no leak down problems, pressure tested cooling system to make sure no coolant in any cylinders. Only thing has bein done was a intake replaced 2000 miles ago. but problem started way after that. i have no vacum leaks, i richen up with problem can see o2 changes, create a vacum leak see o2 change. I have a otc genesis scanner and can watch everything but dont see anything. Help please with ideas

**fkboatman** · 10-09-2008, 08:30 PM

Sorry guys, brand new egr and intake was brandnew from dealer

**skeeter ss140** · 10-09-2008, 08:43 PM

Have the throttle position sensor checked, sometimes they will cause drivability issues that won't show up on a scan, hope this helps.

**ghost28** · 10-09-2008, 08:53 PM

i know this may sound stupid but you mentioned alot of new parts and never once mentioned plug wires......i had one of these give me hell for about 2 months with a mis like you are talking about (mine was and automatic though) and i checked everything until one night i was in a really dark lot late at night and i opened the hood....saw some funky blue light show going on on both sides.....went home and next day changed all the wires and voila....the plug wires run dangerously close to the exhaust manifolds on those cars and can burn a new set in a 15 minute ride.....worth a check.....

**fkboatman** · 10-09-2008, 09:10 PM

sorry forgot plug wires, brand new set have 50 miles on them and they will not burn anything the way they are routed. i swept tps with gragh on my multi meter. Not a glitch

**alwayssomethin** · 10-09-2008, 09:16 PM

is it tuned port w/ long runners or like carb on top of intake. if tuned port check intake air temp senser if messed up acts like choke is on, my dad has 89 corvette w/383 cam heads the works, first three months wouldnt find idle then found that problem and didnt show up on scan. fixed senser and idled perfect well as perfect as cam would let

**fkboatman** · 10-09-2008, 09:17 PM

I got the fix (RAM JET 502) lol and richmond 6spd, now seriously guys please keep ideas coming, because I am just seriously lost and a shamed because I am a ASE master tech also with L1 emission cert. Gm T.B.I is suppose to be easy and simple. I also checked there is tsb for problem through Mitchell or alldata and Gm

**sixpac** · 10-09-2008, 09:17 PM

if you have an otc scanner, what is the block learn count on, while you at it what are the o2 sensor cross counts doing [rapidly from high to low to high] or is the o2 counts slow to cross the .050 volt mark.

**fkboatman** · 10-09-2008, 09:19 PM

car is tbi with 5.0 litre and 5spd. air temp sensor showed within 8 degrees cold or warm then was outside with hood idleing in my shop

**fkboatman** · 10-09-2008, 09:22 PM

dont rermeber block count, o2 I would say was alittle lazy switching back and forth

**Bartman39** · 10-09-2008, 09:33 PM

fuel pressure is 12.5

as measured when...? Idle...? While operating...? Older TBI`s were bad about the regulator spring going south and causing alot of issues... Be sure to test under load as well...

Also did not notice anything about the IAC...?

Darn almost forgot those factory ECU`s around that year had a bad habit of giving techs all kinds of fits too... Saw many that did basicly what your saying and of course never show up on any scanner...