99 vortec 5.7 issue???
 

well ive had an issue with the wifes truck a few times now. it will run rough intermitantly. was on the highway hauling my 20ft enclosed car hauler and she was under load going up hill and started missing, kicked the ses light on. well i checked the ses and it had a random misfire. well thismorning we got up bright and early to take the kids to an amusment park on the other side of the state and it ran fine with a miss here and there. truck sat it the parking lot for 11 hours and we went to leave and the thing wouldnt start. i had to give it a ton of pedal to run and it ran like crap, if i let up it would stall. did this for about 5 minutes and started to run fine. truck has 155k on it with a new fuel pump and filter in the last 5k, plugs-wires- 20k ago. not sure what could be causing this. do ya think its the egr? anything i could clean some sensors with to try to fix? what sensors? im clueless

Re: 99 vortec 5.7 issue???
 

Since you have misfires and sluggish performance. It's time to check the plugs and the fuel pressure both running and when shut off. See that the pressure comes up to the proper level and that it stays there long enough after being shut down.

If you find the plugs are all fouled on one entire side of the engine, you know the problem is fuel related. If you find less than 4 fouled, it's ignition related.

The fuel pressure regulator is located under the plastic plenum. If the diaphragm is ruptured, it will leak fuel into the intake causing rich running and misfires.

Pressurize the fuel system after removing the plenum. You will have to disconnect and reconnect the fuel lines. They bolt on the top and at the rear of the intake. Be sure to check all the connections for leaking under pressure.

While there, also plan on replacing the gaskets between the intake and the heads. I believe these gaskets are different than the crappy plastic ones on there now. http://store.summitracing.com/partde...5&autoview=sku

You'll see those old intake gaskets are not worth a flip.

There are a few other things you will want to check and at least 1 you will now NEED to check.

The rotor and cap need to be changed once per year. Despite what you may have read or heard. Check them for signs of white corrosion.

If the wires have over 50K on them. Change them also. Brand name only.

If the O2s are older than 60K, change them. Don't use Bosch. OEM only.

If you have been running rich, need to check the cats if you still have them. Running rich screws them up big time.

Re: 99 vortec 5.7 issue???
 

Seems like this has been a common problem...thru out some of these threads. I would check the cap 1st. Mines did exactly what yours is doing but w/o hauling anything. Had new plugs and wires but still had the orginal dist. cap lol Changed and running great. Good luck

Re: 99 vortec 5.7 issue???
 

My wife's 99 Tahoe has a similar problem. She cranks over, runs for a second and dies. It seems to only happen 2 times a year. It never runs bad. I'll replace the plugs and wires. When I do the fuel cap, should I go OEM? The dealership says :blah: :blah: :blah: , but I don't want it to fail CA. SMOG either. Sorry to thread jack:( Daniel

Re: 99 vortec 5.7 issue???
 

check the cam position sensor. my 99 yukon had the same problem 6 months ago. misfire code and everything. the cam position sensor is under the dist.cap it was +/- $25. better have some torx bits before you can pull it

Re: 99 vortec 5.7 issue???
 

You gotta love those Vortecs......Ive never been so dissapointed in an engine in my whole driving career. I even bought more than 1 to better the ods. I lost and then gave up!!!

Throttle body and before for me!!!!

Re: 99 vortec 5.7 issue???
 

fuel injectors. if you havent got a tsb from the dealer. the injectors should be under warenty. gm now makes an updated model for the 5.7. the same thing happend to my 97 k1500. it would miss like crazy at high speeds or load. ping like hell too. but if you let this go too long the cats will suffer cost me 1500 just for the repacement cats. that sucked! good luck..:bowtie: :cf:

Re: 99 vortec 5.7 issue???
 

I've otherwise had no issues with this Vortec? It's on it's second time around with 170,---+ on the ticker. Passed CA. smog just fine last month.

Re: 99 vortec 5.7 issue???
 

well just to give an update on my old thread here. i had a bad head gasket. pulled th motor and installed a new gm goodwrench motor. gonna do somthing sick with the 1 i pulled, not sure yet maybe a 383?.

Re: 99 vortec 5.7 issue???
 

I would've put some money in it and got the HT383E, that's what i'm gonna do when my tahoe goes

Re: 99 vortec 5.7 issue???
 

the sub is my wifes daily driver, so that wouldnt of flew with her. got the gm godwrench for around 2k and it has 100k mile warranty. i havnt worked in almost a year and have 4 kids so my piggy bank isnt that big anymore. the engine i pulled will get a 383 kit for a later project thou..

Re: 99 vortec 5.7 issue???
 

my 99 5.3 did this, wouldn't start, and sounded like it was missing or dieing out, wasn't constant though just here and there it was the fuel regulater, dealership part cost me 65 bucks, mechanic put it in for 10 because he had the same problem and knew what he was doin and his boss made him charge me somethin took him 10 minutes to pull in shop and change. apparently common on these years and approximate mileage.

Re: 99 vortec 5.7 issue???
 

Yeah, a lack of cash is getting to be a bigger problem now days

Re: 99 vortec 5.7 issue???
 

sounds like the same thing my 99 5.7 vortec is doing. plugs, wires, cap, and rotor are about 1 year in with few miles, i replaced the fuel pump and filter just a week ago. now ses light comes on and off?? it also has a k&n fuel injection performance kit air filter intake and a borla muffler catback 3" exhaust with 125,000 miles

Re: 99 vortec 5.7 issue???
 

well when i first installed the new engine i still had the problem. since i had replaced the cap, rotor, plugs and wires when istalling the new engine i ruled that out. i also had a new fuel pump so that wasnt the isse. had a code of low voltage on tps, changed it and it didnt fix it. my buddy that work at the proving grounds told me to run 4 bottlrs of injecter cleaner in the tank, so i did it and with in 50-60 miles the studdering was gone, hasnt come back either. he figured it is the poppits dirty/clogged and said if the cleaner worked, that i should then take my upper plenum off and clean all of them by hand or get the upgraded spider. well i havnt done that as i havnt seen the problem come back, but if it does i will put the upgraded spider in.