random multiple mossfire when cold

[upallnight]

Originally Posted by hpy540

as the fuel pump is not variable voltage...... if it runs fine when warm, shouldnt be fuel pump. &, it is not just a miss, it pops and farts and both rich and lean, intake pop &exhaust pop. and only had small missfire issues before i did coolant crossover. & i did not pull Valvetronics solenoids to do coolant crossover. i have done smoke test and carb cleaner spray test.IDK.

At closed loop the 02 sensor is sending commands to the DME as to what it should be doing such as varying the length of the injection time to compensate for either a rich or lean condition. Just because it runs fine at close loop doesn't mean the fuel pump or the fuel regulator is good. It just means that now the 02 sensors are adjusting the fuel mixture to run as programmed. If it is popping at the exhaust that means you have unburnt gas entering the exhaust or an exhaust leak. Keeping driving it like this and you will eventually clog the exhaust because of a too rich condition. Price the cost of new cats for an X lately?

[andrewwynn]

Load the parts cannon. Nice.


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[hpy540]

it is mostly popping thru intake, but some exhaust. anyway i finaly have a hard code. i think i may have broke #6 injector. keeps coming up as a fault, positive to ground. i inspected wires. and tapped on fuel rail to see anout seating injectors some more. IDK. but this is a hard code instead of intermittent.

[amancuso]

IVM issue?

[hpy540]

Originally Posted by amancuso

IVM issue?

What is IVM

[bcredliner]

IVM is the integrated voltage module or integrated supply module. I don't think that is the problem since your symptoms are only present when engine is cold.

Since this problem started directly after the crossover pipe repair I would check my work. There are no coincidences when working on vehicles. You could have a temp sensor connection loose that is screwing up cold start computer input. Check to see if secondary air pump is running when engine is in open loop.

[andrewwynn]

I think he's got a hard fail finally on injector six. I suspect it was just doing a really shitty job putting in too much or too little gas until it finally shit itself now shows up as short to ground. When my CPS failed there was never a direct code just hints but thanks to xoutpost and people that went before me the hints led me right to the problem.


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[andrewwynn]

I think he's got a hard fail finally on injector six. I suspect it was just doing a really shitty job putting in too much or too little gas until it finally shit itself now shows up as short to ground. When my CPS failed there was never a direct code just hints but thanks to xoutpost and people that went before me the hints led me right to the problem.

It's always easier to fix when it hard fails.

[hpy540]

thanx for the input. i will check a few things after the game is over. it did have codes of random multiple missfire before i did coolant crossover. wasnt running real,bad tho. i was just gonna do crossover first, then i figured, do plugs. i dont remember it running horrible on cold start before coolant crossover. but it did have codes.

[hpy540]

https://www.youtube.com/watch?v=cx4UYqKjQa0

why dont people just point to things like this instead of playn games and making you second guess everything