Engine Miss and Starts Hard at Times.

[davbell22602]

97 K1500 5.7L vortec MFI

New plugs, wires, dizzy cap, rotor button, MFI injection conversion kit. All done back in mid sept and mid october. I replaced spark plugs in mid sept. when doing tune up on truck. Then not too long after doing the tune up I started getting a miss and hard starting at times. When I replaced the CFI to MFI conversion I had to replace plug again cause the #8 or #6 cylinder had a plug with broken ceremic around the electrode on the plug. Ran fine for like 2 weeks then since Nov. 2011 it starting the miss thing again. I have a feeling the #8 or #6 is destroying plugs. I use Ac Delco plugs in this truck. The will not stall out when its missing. The wires, cap and rotor button came from napa auto parts store. I also heard that the ethenol gas from the pumps can cause a miss too. I buy my gas from Shell. Just recently switched from regular to plus at shell. I'm getting 330 miles to a 26 gallon tank since switching to MFI.

I'm in auto tech class and thinking I might have to end up putting this on a sun machine at school.

 

[badazzbulldog]

did you remove the distributor when you did the mpfi?

 

[davbell22602]

No. I just removed the tthrottle body and upper intake. The lower intake stayed mounted on the engine.

 

[Tempted]

Checked the fuel pressure? Has the truck been timed? Is the ignition advance working correctly? I personally don't use ethanol in my truck anymore. The stuff was obviously inferior to 100% fuel. You may do a top end cleaning(Sea Foam in the brake booster line).

 

[davbell22602]

I tested the fuel pressure before the MFI conversion. I got 52 at a running engine and 60 when turning on/off for the fuel pressure. The fuel filter was replaced back in May 2011 with the Wix from Amsoil. I was told it had automatic engine timing according to All data. Meaning it sets itself in time. I have no idea on ignition advance thing. How is that checked?

 

[DRAGGIN95]

You have to have a live data scanner to set the timing, it need's to be +or- 2 degree's of 0 or TDC, it's called the cam retard offset.

 

[davbell22602]

You have to have a live data scanner to set the timing, it need's to be +or- 2 degree's of 0 or TDC, it's called the cam retard offset.

Is there anything I should be looking on doing this. We have a OTC Geninus and Snapon modias at school. I know the OTC was able to pin point the misfire on a specific cylinder. The snapon just said misfire but didnt give out which cylinder it was.

 

[DRAGGIN95]

Well there are a lot of thing's I would check, like fuel trim's, O2 cross count's, just basically a complete live data scan to check everything, you need to get some basic figures for what the data is supposed to be though, from a source such as all data so that you know whether a particular thing is out of spec. I don't have the basic parameter's for your truck either, I wish I did.

 

[Tempted]

You have to have a live data scanner to set the timing, it need's to be +or- 2 degree's of 0 or TDC, it's called the cam retard offset.

You can't set the timing manually but you can check it with a timing light. I think the base factory setting is 8* advanced at idle and 0* total at idle. I could be wrong.

 

[TruckinAin4Sissies]

You mentioned replacing everything but the Fuel Pump. My hard-starts were from the pump, that and it was a dog above 70.