vicki711

I just had my motor rebuilt. I have a stock LT1 with the GM hotcam kit and a set of headers and now I have a bit of a misfire issue at warm up. Would it better to get, replacing the current computer chip or the programmer?

shoebox

If you have a 95, your only option is programming. 93 was the last year replaceable chips were used.

vicki711

i have one other problem i have been fighting as well. i didnt go to overboard with the engine mods. i put the gm hot cam kit and a set of pacesetter headers.i also replaced the optispark plugs and wires.since i got the car back i have been dealing with a misfire chug problem only after it warms up .. it chugs bad enough even in 6th gear coastin down hill it bucks.. what would the chances be of my problem being that i havent done any reprogram on the car. what confuses me is i have no check engine lite coming on.

RamAir95TA

A slight misfire is usually plugs/wires related so I would start there. Check for any burning or misconnected wires, then double-check.

You do need programming for the engine to run properly. Not all situations with a cam swap will set the SES light immediately. There also also some codes that will set that do NOT light the SES. Just because the dash light is not on doesn't mean there aren't codes present.

bw_hunter

That bucking in top gear at low engine peers, assuming plugs and wires are good, is likely from the lack of a good tune.....

vicki711

It has brand new plug wires and plugs, new optispark, fuel filter, etc. I just didn't know if I needed to program the chip to compensate for the new cam..if that's why I'm having this problem? It didn't do any of this before the new rebuild.

bw_hunter

You need a tune....

vicki711

I have tuned it, it has brand new plugs, wires and optispark. Would tuning the chip with a programmer take care of the rest of the tuning problem? Or, what is there left to tune? I've scanned it, there are no codes and no check engine light.

Injuneer

How did you tune it for the cam - as in adjusting the tune in the PCM - not a "tune up" (plugs, wires, cap/rotor)? Did you do it yourself, have it mail-order turned or dyno tuned?

The only "programmer" available is the Hypertech Power Programmer, and that can't tune for a cam, and it's not even useful for anything other than gear ratio changes, fan on/off temps, removing speed limiter and rev limiter, etc. Their "power program" has been demonstrated to lose HP.

vicki711

I have not tuned it at all..the cam that is. Could that be what is causing the issues?

bw_hunter

I wasn't clear in post #7....sorry.

The computer has to be adjusted (tuned) to compensate for the characteristics of that cam to ensure the best driveability. The stock program is designed for the stock cam...

The first tune on my engine had it bucking at low rpm under a slight load.Redoing that tune cleared that problem up and I suspect that's what you have going on as well.

vicki711

What is your recommended action plan for this? It sounds exactly like what I have going on. Should I get a programmer for the pcm or take it and have it dyno tuned? Or what..?

bw_hunter

The hot cam is well known to the tuners so you should be quite close with a mail order tune. I used pcmforless.com (not sure if they're a supporting vendor or not ) and they have lots of options on how to get your tune....up to getting a programmed PCM send through the mail so you have zero downtime.

Note: just because I used these guys doesn't meanthey're the best.....do a little research and develop your own opinion.

Locruid

I installed a hotcam, LT headers, 1.6rr and still havent tuned. While I can tell it does need one (running rich), I do not have any sort of lugging. On the contrary the ole girl has been positively terrifying on launching. I have slight surges (not enough to affect drive ability just enough to notice), running extremely rich and as an Auto I'm idling pretty low but other than that she runs GREAT.

Still, you should get a tune regardless. I'm waiting for my taxes to get back

bw_hunter

Remember the gearing differences between automatics and the manuals. Add to that that us 6-speed guys can select any gear at any time...stupidly, of course. Selecting 6-th gear at 55 mph gives you about 1,000rpm...no real power there, especially in a cammed car.

If a hot cam car is terrifying, stay out of something with a big cam!