88 3.0 hesitation

[hanksyota]

ive got a friend with an 88 toyota with a v6 3.0 i believe. the idle is really rough, and dies sometimes, but runs very well above 2500 rpm. a mechanic once told him he thought it was a valve problem, or something about his #3 cylinder. im wondering if it is just carbon build up, and maybe he can run a seafoam treatment or something to clear it out. i know zero about the 3.0, is this common? any other thoughts?

[spindleshanks]

It probably isn't carbon buildup. Seems to me that would cause a buildup in all cylinders, not just #3. Maybe a compression test is in order. Maybe a valve sticking?
I would first check the plugs. Maybe #3 is fouled and the other aren't, which would indicate extreme blowby (worn piston rings) and a fouled plug. Maybe the #3 plug is broken or worn out? Either way, that's the first and easiest way to start a diagnosis. It's free.

[thefatkid]

Valves are comon to go on 3.slows. Not adjusting the valves makes it really easy to burn the exhaust valves.

Do a compression test, leakdown test. Find out what cylinders are misfiring

[RedRunnertc]

Not to contradict Brian, but let's not jump to conclusions here, start with the simple/common stuff:

- when was the last tuneup (cap/rotor/plugs/wires) done?
- ignition timing
- idle speed
- did Wildturkee put the plug wires on? (LOL)
- Seafoam really helps smooth my truck out
- TPS http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

Have him bring it by the HOW next week - I know a thing or two about 3.0's...

[thefatkid]

Not to contradict Brian, but let's not jump to conclusions here, start with the simple/common stuff:

- when was the last tuneup (cap/rotor/plugs/wires) done?
- ignition timing
- idle speed
- did Wildturkee put the plug wires on? (LOL)
- Seafoam really helps smooth my truck out
- TPS http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

Have him bring it by the HOW next week - I know a thing or two about 3.0's...

Hey now, the truck whisperer has spoken! :p It hesitates because it knows it's slow, might as well not give any false expectations. Poor 3.slow.

Being that a "mechanic" looked at it I would hope that he/she would know the difference between a mechanical and electrical misfire. The most common mechanical failure of the 3.0 is the valves (pre-91 headgasket change). Lack of adjustment causes too little clearance, this causes the valve to heat up then burn. Valves dissipate their heat through the seat and too little contact is bad.

TPS-will not cause a misfire but could make it doggy and or a true hesitation.
Timing-if semi close will not cause a misfire but could make it slower then the average 3.slow. If it is was off a lot, it could cause a misfire but likely wouldn't run.
Idle speed-if set too high you could get the lovely fuel cut lope, too low could cause stalling.

Don't spend any money on it till you pinpoint the problem. Throwing parts at it will just get too expensive.

Mama and daughter are going to Disney on Ice, I have some free time on sunday if you need some help.

[RedRunnertc]

Hey now, the truck whisperer has spoken! :p It hesitates because it knows it's slow, might as well not give any false expectations. Poor 3.slow.

:rofl:

Being that a "mechanic" looked at it I would hope that he/she would know the difference between a mechanical and electrical misfire.

Not many mechanics are as good as you Brian ... I don't think this is as good a bet as you would think.

Mama and daughter are going to Disney on Ice, I have some free time on sunday if you need some help.

TAKE HIM UP ON IT!

[Wildturkee]

Just whent through the same problem with my 3.slow...had to do a compleat top end, #3 exaust bu8rnt, #4 intake not sealing...and a few other things, deff ch the compression...

[hanksyota]

thanks a lot for the info so far guys. i didnt even see the thread this weekend, but i will be at the HOW on saturday, and will see if he wants to bring it along for a peek. we definitely have places to start. im also pretty sure he just got new wires, plugs, etc.