Timing problems with TPI L98... Help!

[80Camaro]

I did a tuneup on an '87 Corvette L98. You know, plugs, wires, cap rotor, module, coil (HEI), and pick-up coil. It ran well before except for a little "surging" at idle. The #1 plug wire was in the wrong position on the cap when I took it out to replace the pick-up coil. So, I put it back in the right way after timing the engine to #1 cyl compression stroke. The first indication something wasn't right was the timing mark on the balancer was about 180 off. I even used a straw to be sure the piston was all the way up. And yes... definitely on the compression stroke. By the way, I 've worked as a heavy equipment mechanic for over 15 years and have built many engines in the garage so this type of work is nothing new to me.

Anyway, the engine sort of "kicks back" while cranking, it even broke the starter bendix. When it does crank it idles and revs good and smooth unless you try to "pop" the throttle. Then it stumbles a little then revs OK. I can't get the base timing down out of the TWENTIES and it run descent. I do have the tan elec. timing advance wire behind the distr. unplugged.

This Vette has about 120K on i. These distributor parts came from O'Reilly Auto Parts... they are the lifetime stuff. Do you think it could be the aftermarket mobule and coil? Any suggestions? Thanks

[HILROD]

The balancer ring has probably slipped. GM keeps them in stock. The rubber rings fail. My Monte started to scrape on the timing cover. Also if the timing won't hold steady when checking it, the timing chain is most likely the cause.

[80Camaro]

Yeah, I knew the ring had slipped. But, I made a new mark on the balancer when I had #1 on TDC. Using the new mark I cannot get the base timing down out of the twenties.

[fishtail8]

Not being condescending here, are you sure it's the timing connector you've unplugged? I'd double check that part by having someone unplug it for you while you keep your timing light on the balancer mark. You've got me scratching my head on this one....

[80Camaro]

Well, the tan wire that I have unplugged is right behind the distr. and it's lone. I just had someone say that it's on the passenger side in front of the heater. When I go back over there (brother's car), I'll check.

[MonzaRacer]

Not sure but if I remeber correctly(and dont hold me to this as I dont know which dist you have , small cap or largecap, bit I am curious if you have unhooked the right wire but I dont have Mitchel manual around to double check till Monday.
If i remember correctly the timing mark on stock balancers should be straight up, make sure you dont have wrong tab with wrong balancer too.
If you have a large cap dist the EST line is in the 4 wire connector from the dist.
But something is nagging me in my brain Ill subscribe to this one and keep it in mind.

[WS6]

A tan wire is not the EST wire. The EST wire is Tan and Black. It's not behind the distributor either. To the right(driver's side) of the distributor along the firewall you will come to a relay tucked into the corner right by the wiper motor. There is either one relay or two if the car is a manual 4+3 trans. The EST wire will be right there buried with the relay(s). It could be behind the trans relay which will be the outer one. It is a single line with a single connector. Since you are not getting the timing to come out of the 20s, this shows you still have EST connected. L98s idle between 20-25 degrees advanced while idling. Camaro/firebird L98s have the EST on the passenger side by the heater coil because the ignition coil was over there too.

I'm betting your timing is the only thing wrong. L98s are pains in the ass if your timing isn't right. The reason being is the computer has no idea what the timing really is. It only knows to add a set amount based on the parameters it receives from the other sensors. That's why you have to set the initial timing still for the L98. While you are in there, have you double checked TPS versus IAC counts? What about adjusting the TV cable if the car's an auto? These are simple fixes and adjustments that make a world of difference in how the car runs and performs that a lot of people simple don't get right or over look.

Good luck and let us know if you still have issues. It could be a balancer issues as well, but try to get the timing right first.

[MonzaRacer]

Thanks WS6 I had a brain fart on wire color and location. AND i do agree with the whole run down, vary the timing morethan a few degrees and the car will run like dookey, and I agree with the TV cable adjustment too.
Oh and cheap modules inthe dist will create major havoc, I havent had any problems from Echlins from NAPA and AC Delcos but pretty much any others you take a chance of it NOT being stable enough.
Good Luck.

[WS6]

No problem. I actually never found the EST disconnect plug on the 87 vette project car we have until I gutted the entire car and found it sitting between the fuel pump relay and 4+3 OD relay. I looked and looked all over the car when we were still running the L98 and just never found it. Finally just gave up and used Diacom(DOS based data logger) to get the timing down to 6 degrees between TDC timing and reference timing. I was peeved when I moved that OD relay and found it sitting there.

[80Camaro]

Thanks alot guys, I haven't been back over ther yet but I will this weekend. BTW, the car is an auto with the large cap. I'll check the TPS and cable adjustments too. Thanks again!

[MonzaRacer]

tricky little *******s aint they?