breaking up, stumbling, surging! wtf!

BoostedSUV

BoostedSUV

Active member
Not really sure where to put this but I will start here...

Drove my truck home friday night and it was running awesome! Got my new Autometer elec FP gauge in the mail so I decided to put it in. I took out my useless A/F gauge and the signal wire I had T-tapped to the purple wire at the ECM. Installed the FP gauge with out issue and fired truck up, Fuel pressure looked good, gauge worked so I parked the truck. I went to drive the truck to work this AM and it barely made it. It was surging, breaking up, and stumbling real bad until it hit 2500rpm then it jumped to 3000 and cleared up. Did this the entire way to work and home.

I checked all the wires at ECU and everything looked tight, everything was plugged in at Engine bay, and I just used the existing wires I had to the A/F gauge to run power and lights to the gauge. There's no rhyme or reason to this issue!

Datamaster shows the truck going dead lean when its breaking up... O2 counts in the 80's and s-term counts jump to +42 until it hits 2500rpm!!! Everything else appears to be normal! Any ideas?? I planned on bringing the truck to the track on thurs since I finally got it running awesome and now I have this set back... It's barely drivable as it sits! TIA
 
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BoostedSUV

BoostedSUV

Active member
Re: All I did was change gauges! WTF!?!

Re: All I did was change gauges! WTF!?!

This is my only means of transportation to and from worrk... anyone have any ideas? I can email the Datalog file showing what it's doing...
 
BoostedSUV

BoostedSUV

Active member
Re: breaking up, stumbling, surging! wtf!

c'mon fellas.. help a kid out on his birthday! haha I need to figure this out so I can get to work tomorrow!
 
Quickstop [UK]

Quickstop [UK]

Combating adversyty.
Re: breaking up, stumbling, surging! wtf!

take it out and reconnect the old thing and see if it goes back to normal.

what did you do with the purple tap wire?
 
1madgumby

1madgumby

New member
Re: breaking up, stumbling, surging! wtf!

Quickstop [UK] said:
take it out and reconnect the old thing and see if it goes back to normal.

what did you do with the purple tap wire?
Click to expand...

Sounds like some fuel problum. like he said put it back the way it was & try it agin. if it fixs it there is A problum with the parts or install..just my .02
 
BoostedSUV

BoostedSUV

Active member
Re: breaking up, stumbling, surging! wtf!

I checked every vacuum line 10 times to see if I knocked something off and everything looks good. I even put in the other gauge for sh*ts and giggles and that did nothing. I swapped out the coil with a spare I had and that did nothing. Something like this I would think is an obvious find. All I did was swap out gauges and remove a wire I had t-tapped into the ecu for an O2 signal wire.
 
WyoSyclone

WyoSyclone

Active member
Re: breaking up, stumbling, surging! wtf!

Are you sure something else wasn't attached to that t-tapped wire.... with your mods (3-bar, etc.) I would guess you're running a WBO2, but it's not listed.... You went through the firewall somewhere for the wiring for the FP gauge - if you pulled on a wire maybe you nicked some insulation?? Kind of shooting in the dark - I'd just go over every inch of everything that you touched.
 
BoostedSUV

BoostedSUV

Active member
Re: breaking up, stumbling, surging! wtf!

Rob I went over everything with a fine toothed comb. Its obvious I am missing something because there is no reason my truck would doing this. I have the PLX wideband in a box in my room, I just got it last week and have had a chance to install it yet. That is next weeks project. The only thing I touch by the ECU was a wire had tapped into the O2 signal for an A/F gauge I had in the truck (it was a freebie). I ordered the elec FP and the wideband at the same time. I'm going to check everything again. I had to have pinched a wire running through the firewall or something.
 
WyoSyclone

WyoSyclone

Active member
Re: breaking up, stumbling, surging! wtf!

Could be an intermittent connection of one of the terminals in the ECM connectors.... what a b*&tch to trace one of those down. Is the ECM hanging or is it up in it's 'nest'?

If it stumbles while idling (and if it will keep running) you might want to wiggle/push each wire going into the ECM connectors to see if the problem disappears...

good luck, that's a tough one track down.
 
BoostedSUV

BoostedSUV

Active member
Re: breaking up, stumbling, surging! wtf!

The Ecu is relocated to the glove box. Truck idles fine and even feels ok under power. It just breaks up and surges at part throttle during normal driving... I don't get it?
 
WyoSyclone

WyoSyclone

Active member
Re: breaking up, stumbling, surging! wtf!

Maybe reset the IAC? If it idles fine and is OK under WOT, then maybe the IAC is working wrong, affecting AFR's at part throttle??
 
BoostedSUV

BoostedSUV

Active member
Re: breaking up, stumbling, surging! wtf!

How would I reset the IAC? I've never done that before. I was just thinking back and I had a real hard time trying to push the FP gauge harness through the opening in the firewall so I had to go through and another access hole. Its very possible I could have pinched a wire or knicked the wire. Among the wires I have going throught the fire wall there are the power wire for the ECU voltage fix and a tach signal wire hooked to the coil for the remote start. Either of those could cause this issue so I will go back and examine them closer...
 
berzerker

berzerker

wookie
Re: breaking up, stumbling, surging! wtf!

i,m going with bad fuel pump , mine was doing the same thing . also do the intank pump wiring harness while your in there .it will save you headaches in the long run . only cost's ten bucks from napa .
 
1madgumby

1madgumby

New member
Re: breaking up, stumbling, surging! wtf!

Mine has done the same thing in the past & it turned out to be the plug wires, looked like new but were junk, changed the wires & bam fixed it. Put A new set of wires on it & cap & rotor, sounds like it is running out of fuel, also tht AF gauge might be grounding out inside sending A bad signal to the ecm & the ecm is changing the fuel, pull the gauge & try it then, if it does the same thing change the wires.
 
sly dvl

sly dvl

Ya, it's got a Turbo
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.
 
BoostedSUV

BoostedSUV

Active member
Re: breaking up, stumbling, surging! wtf!

Ok I'm still going at this with no luck... I checked all the wires running through the firewall and nothing was pinched or knicked. Nothing appears to have grounded out or shgorted. I pulled out the FP gauge and that did nothing... I checked all the connections on the back of the ECU and couldn't find anything loose or broken off.
 
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