Ok so i have been having trouble figuring out why my car is lurching when i am cruising down the road. It feels like im pulling a goose neck trailer. Also, it take a lot more cranking to start it cold and it will not start at all when its warm. on acceleration it runs fine and it idles perfect. and another thing, when i have it in park and rev it up a little, at about 3 grand it starts to sputter but if i give it alot of gas when i rev it its just fine.

Im about positive its in the ignition somewhere so i have replaced the pickup coil and the ignition module inside the distributor. Its helped out by a msd 6al box and a new msd coil.

Im out of ideas of what it could be... any help would be very helpfull... thanks

 

Sounds like your running a bit rich. I wouldnt be supprised if you pulled your spark plugs and found they were a bit on the dark side. I bet if you open the throttle a bit when you try to start it it will start easier as well (depending on your fuel injection set up though some really dont like it when you hold the throttle open while you try to start it).

 

this isnt a tuning issue... it was running just fine a couple weeks ago. Something quit working.

 

Well I never claimed it was a tuning issue necessarily. For example suppose for a moment a fuel pressure regulator diaphram ruptured that would be dumping fuel into your intake causing you to run rich. Point is I know problem your describing and the car sounds to me like its choking on fuel. Why is the question but the first step is to confirm that by doing things like pulling spark plugs.

 

the first thing i did was check the spark plugs thinking maybe they would be fouled but they looked fine. They were a little brown but thats from the octane boost i have to run with my compression.

 

Well I still think your cars getting flooded. At this point it might be a good idea to provide a few details on the car? According your your sig youve got a stealth ram. How is it controlled with factory TPI stuff or what?

 

its a 383 with aluminum heads, zz409 cam, 11.3:1 compression, holley stealth ram, kirban fuel pressure regulator, 30lb injectors, shorty headers, tpis tune.

 

Well thats a good start but I was hoping to know more about what controls your FI system. I mean are we talking speed density or MAF. Factory GM TPI electronics or maybe something from holley?

 

i got an adjustable MAF and just a new gm computer that tpis modified to take the chip they made for it

 

Ok well thats good what about everything else? I take it a used factory TPI harness and factory sensors aside from the MAF? Also just out of curiocity have you tried disconnecting the MAF sensor and seeing how it runs without it? My point in suggesting this is I've heard a lot of complaints about the adjustable MAFs and by disconnecting it your forcing the ECM to run of of preset defaults values rather than actual signal information from the MAF sensor. In theory if the ECM was programmed correctly and the MAF sensor was bad it should run better (although obviously not perfectly). Also are there any stored trouble codes? Remember you cant go off the check engine light because even if the light is off codes may be stored. lastly whats the status of all your emissions stuff I'm guessing all removed and programmed out of the ECM?

 

Wow start simple check fuel pressure check filter or just replace their cheap enough

 

yea harness and sensors are all factory. some replaced some not. ill try the unhooking of the MAF. i done that with my 305 in the car and i ran .5 sec slower in the quarter. And for some reason the computer tpis gave me doesnt give a check engine light or codes. idk why. As for the fuel pressure. its fine. its got a brand new fuel pump in the tank and also if it was lacking gas it wouldn't run fine when i mash the throttle. Thats my theory anyways...

 

Yea I'm not surprised you lost .5 in the 1/4 mile with the MAF disconnected. However it speaks volumes for GM because considering without the MAF they are just running off default values they figure are good enough its surprising it ran as well as it did. On the trouble codes, I am very disappointed to hear you say that but I think I know what may have happened. See some of these codes fault conditions are relative to the motor. So when you get into a more wild build like the one you've got if the trip conditions were left alone it may trip codes when everything is fine just because the ECM is comparing what it expect to see for a factory motor. Also without the emissions hardware they would trip codes as well. The easy solution is to disable the diagnostics when programming the chip. Now I'm kinda surprised they would do that as that makes any future troubleshooting nightmarish at best and I would want to give them a call to see if thats what they did because you may have some other problem that would explain why there's no check engine light.

 

im in the process of buying an ostrich 2 set up for my car so i can tune it myself. It seems when ever i have someone else do something for me they end up screwin it up somehow.