kc5jmr

I have a 99 Suburban 4x4 k1500 with a 5.7l Vortec V8 engine, what I have done so far to it.
1. replace the fuel pump and fuel filter
2. replaced the intake manifold gasket
3.replaced the distributor cap and rotor, cables and plugs (used Delco plugs and Bosch cables)
4. replace both pre cat o2 sensors
5. replaced the ECU twice (turns out the first one was defective)
both were properly flashed and the second one also had the Crank case position sensor variationdata relearned.
6. replaced the knock sensor on the block by the starter.
7. replaced the Coil and tested the ignition module
8. had the Catalytic converters checked ok

Now the problem:

normal driving is fine up to a point when the engine has warmed to normal running temp. Then a sudden power loss occurs but now Error codes pop up
prior to the computer change out were were getting a #4 piston misfire, bank 1 sensor 1 bad, bank two sensor 1 bad bank 1 sensor 1 low voltage reading #1 piston misfire. After changing the computer for a second time a po1336 (Crankcase position variation data need to be relearned) that the $140.00 at the local autoshop with a tech-2 scan tool ) Still have a serious power loss. Running my own OBDII testing software reveild that the Log term and Short Term fuel Trim was running rich. Checked the fuel pressure with the ignition on at 60psi and it would drop to about 55ps when the engine starts and it stay in the general area whil the engine idles. when the vehicle is in park the enging will rev up to 4000 rpms and hold stable but when the vehicle is in gear it has trouble going up to 3000 rpm and at it's tries to stall out and won;t go above 1000 rpm almost no power to move the vehicle at all. The strane part is that if while I am driving (and I don't recommend this at all to anyone) putting the car in neutral and cutting off the engine for about 10 to 20 seconds and restarting, placing the vehicle in drive and it will go for a little longer till it try to die again. I suspect the CSFI but short of replacing the metering body and the fuel pressure regulator I have no way to test the hypothesis, nor do I have the resources to keep replacing the parts. So I ask is it sound like the CSFI need to be looked at or could it be something else.


KC5JMR

maxxman04

run a compression test. check for codes. even if light is off there could be codes stored.

kc5jmr

I checked for any codes and got none t all nd I don't have the compression tester

kc5jmr

I still think it is the SFI but I was changing the spark plug cables again and I noticed that the Distributor was loose, so i tightened it down and it seems to be running better now. I won't know for sure till I go to the dentist next week, and I will need to drive a longer didtance then my test drive was. I hope it is this but I did notice on the last system scan that both the Long term and Short Term Fuel trim were reading rich. and while I was inspectin the #4 pistion spark plug I noticed it was a little damp but no real buildup on it and it was the only one that smelled of gas and not of exhaust.

KC5JMR

73shark

Could be some or all of the injectors are dirty and not completely shuting off thereby allowing extra fuel into the chamber. If that's the case, I'd run 2-3 bottles of Techron thru one tank of gas. If that doesn't help, then either it's not the injectors or they're so dirty it didn't help.

kc5jmr

I have to admit that it is driving better then it has in the past few days, but it still is not running the way it should. The Fuel Trim both Long and Short Term show that it is running rich. and I rechecked the #4 Piston Spark Plug and it still seemed more damp then the rest. I noticed the last set of plugs was the same way the #4 was just a little more damp and smelled of Gas. I am willing to bet that it is the #4 poppet that is stuck partial open and it is robbing fuel from the rest of the engine which is causing the ECU to force it to run rich. I will give the Techron a try and see what it does, if it does not work I will have to open up the intake and either try to clean it out or just upgrade to MFI


KC5JMR

maxxman04

having done the mfi upgrade, i'd do it. you only have to pull the upper plenum off. 3 maybe 4 hours work. them poppets suck. the mfi, awesome.

kc5jmr

Where did you get the MFI conversion from and what did it cost you.

I am very sure it is the CSFI now, when the car would loose power and not even get past 1000 RPM (and once again I say don't do this at all), I put the vehicle in Neutral and cut the engine (KOEO) and wait for the odometer to read 0 MPH count to ten and restart the car this gives me a return of power at least till I can get to where I am going. NOw all I have to do is find a MFI upgrade that won't rape my check book


KC5JMR

kc5jmr

Well I finally got the MFI conversion for my 99 k1500 Sub 4X4 and it seems to be working out. I spent the better part of Saturday pulling the upper intake off by removing all the stuff around it like the brackets and coil pack but i was able to get it off. once I was able to get the to CSFI unit itself it was a breeze to remove it. Of course once I was able to remove it it started to fall apart on it own. As i looked at the inside of the Manifold the front was black with soot it wiped out ok but the rear was damp with fuel residue. I cleaned it out as well and installed the MFI unit and it was a breeze for the most part. The only difficult part was to route the injectors to the proper ports. I double checked and triple checked each one, and then when I was done I even checked again. Getting the upper intake back on was a bit of a challenge, the O-ring that is placed around he top of the MFI makes it difficult to reinstall the plastic uper section but a little petrolum gelly and it slidd on without a problem. it was around 19:00 hours when I finally finished reinstalling everything including moving the AC compressor back into position. took it for a test drive and called it a night. This morning I ad to go to the gas station, and it had no hesitation at all. I also need to watch how fast I am going, on the highway I was at about 1700 to 1800 RPS and going over 70MPH. It all feels different now. To recap all that I have done.

started with replacing the ECU which I don't think I needed to do after all
got a defective ECU (that was new) only to find out after replacing it that it's replacement needed the Crankcase Variation data inputted (neede a GM Tech 2 scanner to tell the ECU to start reading it) that was a $140.00 bill.

then replaced O2 sensors

and then the Plugs cap and rotor and then the coil which after I did, blew out the intake manifold gasket, and that was a whole different story. and during the reassembly of the upper intake I found that the distributer was loose and needed to be tightened down. Now with a quick prayer to God and a seriously sore set of muscles I pretty sure I got the problem solved. I get back in a couple of days to let you all know weather it was all good or not.


Robert