Engine pop and smoke on startup 99 Tahoe
This is a successful solution to an archived thread "Engine pop and smoke on startup" posted over two years ago.
Here I am back after over two years to tell you I fixed the problem and best of all it was a $44.99 part. It was tough diagnosing this problem especially when it was inconsistent the occasional pop then white smoke pouring out of the throttle body (TBI) under the hood. I always thought this reminded me of trying to start a flooded traditional carb that would pop and then smoke. Consistent tough starting was always evident when the engine was warm, cold starts seemed pretty good. It always just seemed like it wasn't getting enough fuel on starting.
I Tried the dealership three times they poured through GM notices/bulletins nothing that matched (although I wonder how hard they looked). They had no idea they tested fuel pressure and I did a complete tuneup. Over the course of two years it became worse the popping and smoke on startup out of the throttle body and the rough idling. It finally got to the point about 2 months ago that the check engine light finally stayed on consistently. All the codes indicated that the O2 sensors needed to be replaced and tons of misfires but the code readers would not indicate specific cylinders. So I replaced all of the O2 sensors up and down stream of the cat. That seem to help but did not solve the problem. Even my most trusted mechanics (not dealer) suggested since the 5.7 had just over 150k maybe it was time for new vehicle. They actually helped me narrow it down to the final two possible solutions. I thought yeah just what I want another car payment with one in college. Not to mention this 99 Tahoe is immaculate because I really took care of it mechanically and other wise.
Finally with allot of research I determined it was one or two things. First and foremost the Fuel Pressure Regulator and second the Spider injector system. The engine ran great when it was rolling down the highway and was strong. I also felt if it was one or two bad injectors the codes would not indicate misfiring all over the place. I decided to purchase the Fuel Pressure Regulator at $44.99 and a Fel-Pro Manifold Gasket set $57.99 at AutoZone. At over $200 for a rebuilt spider injector system or $320 for one at AutoZone I decided to take a gamble. I decided I would only replace the FPR and check each injector while I was in there. Then if it doesn't completely solve the problem I would have to go back in and remove the plastic intake all over again and replace the spider injectors. Since the brand new gaskets for the upper plastic intake would be reusable I would only be out my time to take everything apart again. I could live with that especially if I could save $320 on the spider injector assembly.
I removed the plastic intake labeling all sensor plugs along the way. I found the FPR had been leaking as evident directly below it. The valley casting below it was bright and clean were the fuel had been dripping out the overflow on the FPR. I pulled each injector and inspected them cleaning each any way with some spray parts cleaner along the way they looked great. Although they should have been after all of the fuel injector cleaner and Sea Foam I dumped in over the years hoping it would help this problem.
After I put everything back together and buttoned it up it started right up. Quite a bit of white smoke came out the exhaust from the cleaner. That all went away soon enough. Then it was time for a test drive. While idling it was finally very smooth. Took her out on the highway for a test drive and I was extremely happy with the performance plenty of power. Then on the way home the check engine light went out (even happier now). The final test would be how would she start while warm. I'm happy to say it starts like it did when it was brand new.
So for a days worth of time and $103 later I have my 99 Tahoe back and running like she did when I first bought it. I am thrilled to say the least. This was a frustrating problem and I hope this helps someone else out.
Last edited by smithsclassic; 05-09-2010 at 08:29 AM.