injector control?

[gjp]

This goes part with my misfire issues but I hope to get more response by creating a new thread. Sorry.

When my truck is cold it runs fine. After warm up it runs bad(misfires). When its cold and running fine and I pull an injector wire It mimics the misfire except the misfire is at a faster rate. Because all the plugs look the same I feel its a random misfire of the injectors. The question is, What controls the injector fire sequence and because the injectors are ground pulse activaded, where is the ground wire controling them. I checked all the grounds before but I would like to isolate the specific ground wire. If the bolt or screw gets lose when the block gets hot that could cause the problem. THANKS

 

[leroy]

Re: injector control?

The injectors are batch fired by the ecm, and grounded at the ecm.

Jim

 

[gjp]

Re: injector control?

Thanks. Where is the ecm ground?? Also Anywhere I can find the color code to the wires. The ecm is sitting on the floor of my sy right now. Thinking on getting a new ecm. Does the chip control the injectors??

 

[leroy]

Re: injector control?

http://www.syty.net/forums/showthread.php?t=35536&highlight=ecm+connector

The chip controls the injector pulsewidth through the injector drivers.

Jim

 

[gjp]

Re: injector control?

So if it is a the injectors. COULD a new ECU fix it. or would the problem lie in the chip. The truck does it with the phil or stock chip installed. Its worse with the phil and 50#'s. Since the stock chip is still connected could that be the problem. BTW thanks for the help. This would have taken me days of searching.

 

[vortecfiero]

Re: injector control?

hmmm runs like crap when things get warm...
fuel pressure...
oxy sens
and the cause of a misfire i had once - ignition module
it was fine cold but a little heat made it misfire

 

[gjp]

Re: injector control?

All that has been changed. It has a new ignition system.(dist,ign mod., cap,rotor,wires,plugs)
afpr set at 45. FP is at 37 at idle with vac line installed. Has new 255 pump, filter, and injectors.
Phil chip disable o2 sensor and egr. O2 was replaced last year.

 

[leroy]

Re: injector control?

I'd suspect something other than injectors. It never hurts to have a spare ecm for a substitution test, thought.

Check the grounds by the thermostat and the back of both heads.

Check the ecm voltage with a scantool. Low voltage can cause problems.

The ignition module is also suspect, even though it's new.

Jim

 

[gjp]

Re: injector control?

Its the 2nd module I tried. both new. DM shows 13.6v at idle. I have been working on this problem foe 5 weeks. It has to be a fuel delivery problem. when I pull the injectors one at a time while its missing I hear no change. When its cold and I pull one it stumbles hard.