breaking up, stumbling, surging! wtf!

[BoostedSUV]

Re: breaking up, stumbling, surging! wtf!

Have you got a vacuum/boots gauge (not the factory one) hooked up? What does it read at idle in park, and during light accel. when things are acting up?
Also, is your EGR functional? If so, try disconnecting it (remove & plug the vac line) and see what happens.

Yes there is an Autometer boost Gauge, it reads -15 at idle in park. When I slowly bring up the RPMs the needle will drop to about -18 then the truck breaks up at 1100, 1900, 2400 everytime and seems ok in betweenand above those RPM's but the vac reads -15ish when it's breaking up, I can steadily increase the throttle but theres a delay before the RPM will increase.

I have an EGR delete and the entire EGR system has been removed from the truck.

 

[BoostedSUV]

Re: breaking up, stumbling, surging! wtf!

Something I just Noticed... Probably unrelated but happened at the same time. My interior lights are not coming on with the driver door, the chime works off the door jam switch with keys in ign but the courtesy lights aren't. I can turn them on with the switch, or pass door or keyless... These always worked prior.. Probably unrelated but I will mention it.

 

[BoostedSUV]

Re: breaking up, stumbling, surging! wtf!

changed to a brand new spare MSD cap, Changed coil wire and Coil... still no good.

 

[WyoSyclone]

Re: breaking up, stumbling, surging! wtf!

Did you pop the top off the ECM and make sure the MEMCAL hasn't become disengaged/unlocked?

 

[BoostedSUV]

Re: breaking up, stumbling, surging! wtf!

I checked the memcal, it was secure. I even tried a different eprom in my Moates adapter as well. I even tried the stock memcal and had the same results. I would love to have a spare ECU to try... Of course I just sold my spare 2 weeks ago because it collected dust for 3 years!!! :rant:

 

[BoostedSUV]

Re: breaking up, stumbling, surging! wtf!

I Just ordered a remaned ECM from GM. I will give that a try and hopefully that will fix it. Now it will probably be a waiting game for then next few weeks before I get it! :rant:

 

[qbnkiller]

Re: breaking up, stumbling, surging! wtf!

I had the alternator take a crap on me....ran like shit for the drive home. Gauges danced a little bit, voltage went up and down quite a bit.

Might be worth a trip with it to Vatozone...

 

[BoostedSUV]

Re: breaking up, stumbling, surging! wtf!

Well I OHM tested all of the spark plug wires last night... All 6 were between .09 and .13 ohms which means they aren't an issue. I checked the coil wire and that was 7.24!!! Obviously the coil wire was bad so I changed figuring that was my problem. Truck idled so much better so I went for a ride... Unfortunately I had the same thing going on but didn't seem to be as bad? It also seemed to start surging around 2600 instead of 2400... Does this make any sense? I will have the new reman ECM tomorrow so I'm crossing my fingers!

 

[WyoSyclone]

Re: breaking up, stumbling, surging! wtf!

How would I reset the IAC? I've never done that before..

Sorry, my mind was thinking of another issue on this one - not applicable here- but here is the procedure anyway...

a. depress accelerator slightly
b. start and run engine for five seconds.
c. turn ignition off for ten seconds.
d. Restart engine and check for proper idle operation.

this is used after replacing IAC with new unit.

 

[BoostedSUV]

Re: breaking up, stumbling, surging! wtf!

New ECU is in, still having the issue but it seemed to get better. Still don't have courtesy lights working when I open driver door... Could be coincidence but it all started at the same time!

 

[BoostedSUV]

Re: breaking up, stumbling, surging! wtf!

finally got around to installing my PLX wideband... It shows exactly what the Datamaster file shows. The truck is going lean and breaking up. Truck Idles at 14.5 to 15.5 and when I bring RPMs up it goes to 18+ and I can hear the truck breaking up. Once it's past 2600rpm its read 13.5-14.5.... still stumped!

 

[berzerker]

Re: breaking up, stumbling, surging! wtf!

bad fuel pump !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[BoostedSUV]

Re: breaking up, stumbling, surging! wtf!

bad fuel pump !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

if you took the time read this thread you would see that this all started after installing a FUEL PRESSURE gauge in my truck... Don't tou think if the pump was my issue I would see in on the FUEL PRESSURE gauge I just put in the truck? Base FP is 50lbs, its at 38ish at idle and 42 when I bring up RPMs to the point it starts breaking. Fuel pressure is not the issue....

 

[attackdog]

Re: breaking up, stumbling, surging! wtf!

plugs are gapped at .025. Just did them a while back so I'm sure of it

If I am not mistaken, I believe the plugs should be gapped at 0.35. I may be wrong so if others could verify, that may be one of your issues. Also, What was the purple wire plugged into and was it a ground or 12volt connection? You may want to reconnect that wire! Hope this helps you out.
-Dean

 

[attackdog]

Re: breaking up, stumbling, surging! wtf!

New ECU is in, still having the issue but it seemed to get better. Still don't have courtesy lights working when I open driver door... Could be coincidence but it all started at the same time!

I have that problem every once in awhile. The fix for me is to twist the pin switch in both door jams until the dome lights turn back on, the try to give them a little tightening.
-Dean

 

[attackdog]

Re: breaking up, stumbling, surging! wtf!

if you took the time read this thread you would see that this all started after installing a FUEL PRESSURE gauge in my truck... Don't tou think if the pump was my issue I would see in on the FUEL PRESSURE gauge I just put in the truck? Base FP is 50lbs, its at 38ish at idle and 42 when I bring up RPMs to the point it starts breaking. Fuel pressure is not the issue....

You may want to adjust you AFPR to 41lbs at idle.
-Dean

 

[BoostedSUV]

Re: breaking up, stumbling, surging! wtf!

Dean the plugs were gapped at .035 but I was getting spark blow out and I had to tighten the gap. Truck ran great fro last year or so after tightening up the gap. The purple wire on the ecu I was refering too was the O2 signal wire, I didn't disconnect it I just T-tapped into to feed the A/F gauge that I used to have in place.

 

[BoostedSUV]

Re: breaking up, stumbling, surging! wtf!

I replaced both door jam switches and the lights still wouldn't come on with driver door, only passenger door. I just ran a jumper wire from the jam switch to the ground wire of the courtesy light circuit and now they work. Not really sure why they stopped working in first place but it wasn't the switch...

 

[BoostedSUV]

Re: breaking up, stumbling, surging! wtf!

Still haven't found a remedy... Going to try to change plugs and see what happens. Only thing I can think of is there's a ign miss causing the ecu to think its lean. Just a guess...

 

[ircwet]

Re: breaking up, stumbling, surging! wtf!

Mine was acting funny last week....it was randomly cutting out under acceleration. I did have a loose ground from the battery to the back of block. The ecu gets its ground from the stud on front of the block. I also added another 4g battery cable from that stuf over to the fender using the bolt for the ABS. Things are running great now....