Topic: Son's 88 running on only 5 cylinders (original post)
in Forum: C4 Engines
Already a Member?
Click Here to Login
Not yet a Member?
Click Here to Register for Free!
My son just rebuilt his '88 engine this winter. Now he has it running.....kinda. It is missing on three cylinders. The plugwires and plugs have been changed, the injectors are new and will work when placed in other cylinders. He can change the injector plugs (It is a batch fire setup) and that makes no difference. The valve lash has been adjusted/readjusted and the movement of all the rocker arms have been measured and they are all opening the same amount.
|UPDATED|7/4/2012 8:41:19 PM (AZT)|/UPDATED|
So...I'm guessing that it MUST be something with the timing. 
Any ideas?
|UPDATED|7/4/2012 8:41:19 PM (AZT)|/UPDATED|
SPONSOR AD:: (Our Sponsors help support C4VR)
Standard Member
Moderator
Send PM
Moderator
lanoka harbor, NJ - USA
Joined: 3/22/2009
Posts: 1363
Vette(s): 1990 L-98 white/ red/black leather interior targa top auto
1975 L48 blue/black leather interior t tops auto
by any chance has he checked for any codes that the ecu might have put out. i would check the wires first. even though they are knew never can tell you might have gotten a bad set. would also take an inductive timing light and check each wire from the cap to make sure each is firing. few basics would be to check that the wires are in the right order and on the right place on the cap. just a few suggestions.
dave
dave
the dynamic duo
c3vr life member #97
eddie20890 said: by any chance has he checked for any codes that the ecu might have put out. i would check the wires first. even though they are knew never can tell you might have gotten a bad set. would also take an inductive timing light and check each wire from the cap to make sure each is firing. few basics would be to check that the wires are in the right order and on the right place on the cap. just a few suggestions.
dave
dave
No codes. Used old wires first and then new wires second. Checked, rechecked AND rechecked that wires in right place and firing order. Haven't used the timing light yet. He updated to ram-air and larger injectors during the rebuild and he has checked and rechecked all of them. It also has a mild cam added.
Is it a steady miss at any rpm ? Or does the engine seem to smooth out once you come off of idle ? I would check for a vacuum/intake leak...EGR valve partially open etc..... if in fact it does clear up at higher rpms. I wouldn't think ign. timing would cause it to drop 3 cylinders unless it was wayyyy off JMO 
SAYWHEN said: Is it a steady miss at any rpm ? Or does the engine seem to smooth out once you come off of idle ? I would check for a vacuum/intake leak...EGR valve partially open etc..... if in fact it does clear up at higher rpms. I wouldn't think ign. timing would cause it to drop 3 cylinders unless it was wayyyy off JMO
It is a steady miss all the time. He just took the intake off and resealed it yesterday and no go. He's taken it to a shop to see what they can find.
I hope it is just something super simple that we haven't thought of.
I remember reading on another thread that compression had been checked and ok. Since the plugs and wires have been changed...firing order checked and rechecked...injectors are new and also checked and rechecked...i'm guessing the dist. cap has also been checked and/or replaced.
If he doesn't have a vacuum leak and the entire ignition system is correct.....then maybe a tight valve....I know valve lash has been checked and rechecked...I've also seen it give some pretty good techs fits before... trying to follow a cam manufacturers instructions. JMO
Anyway good luck to your son...and keep us posted on the results....i'm sure he's crazy for a test drive with the Vette hittin' on all eight cylinders after all the work he's done. 
I got a cap that was defective once...check the cap for continuity
Remember, there's no place like ~ ;)
in Forum: C4 Engines
SPONSOR AD: (Our Sponsors help support C4VR)