intermittent loss of power

D

Damian

Member
Im having an issue that just started recently. When I take off, sometimes, Ill get whet feels like a huge loss of power. It feels like Im getting a ton of knock retard, but my log shows zero knock. Any ideas? I tried to upload the DM file but it says its invalid.

Mods:GT37 with front mount IC, A/C delete, all ignition stuff is new, 3 Bar MAP sensor, AEM wideband (not hooked up to ECU), and AEM TruBoost.
 
D

Damian

Member
Re: intermittent loss of power

Driving home earlier, when this crap happened, the lights would flicker and the a/f ratio would go super rich. The CEL would flicker on and off but nothing stuck to be able to read it.
 
jaystcb

jaystcb

Sy 0902, 92Ty 0909
Re: intermittent loss of power

Almost sounds like a bad electrical connection. My truck was doing something similar a while back. My Sy would just shut off. like someone flipped a switch when I was driving. In my case it turned out to be in the ECU. One of the prongs that the chip connects to was bent and not making a connection to the chip. I have an extra ECU that you can try for trouble shooting.
 
Don W.

Don W.

Stab it and steer it
Re: intermittent loss of power

It is sounding like electrical. I have a known good ECU as well. Not for sale but I'd be happy to loan it to ya. (FYI I know it's good because I've run the truck on it.)
 
Matt

Matt

Active member
Re: intermittent loss of power

checked that the ecu chip is fully seated a loose chip can give you similar loss of power issues
 
D

Damian

Member
Re: intermittent loss of power

I have a brand new P680 battery and a 200 amp alt that doesn't have but 5000 miles max on it. I didn't look at the voltage to be honest, I'll look at the log and see, might even take it back out for a spin. If I drive like a 90 year old lady, it drives fine. It feels like if I give it a certain amount of gas, it starts acting up after that. Say 0-10% throttle, everything is fine. 11% and up is terrible.
 
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Damian

Member
Re: intermittent loss of power

MikeRenz said:
is it only when low amount of fuel in tank? fuel slosh starving the pump
Click to expand...

Tank is full. It started it when I had about a 1/4 tank, but it never did that before and I've gone below 1/4 and punched it. But I filled it up anyways with no change but it has been slowly getting worse. Now I don't even want to think about driving it, but I have to get it fixed soon though.
 
D

Damian

Member
Re: intermittent loss of power

I just looked at the log I did last night while being parked in the garage. I was still able to get it to do the rich condition and lights flickering. The voltage holds right around 13.6-13.8 volts.
 
D

Damian

Member
Re: intermittent loss of power

I had a problem before and it just went away until today. I went out to start the truck up and the fuel pump didnt kick on. It did this a couple weeks ago but then it just started up out of the blue. I checked the fuses, all were fine. So, it didnt start, then I went back out 30 minutes later and it fired right up. Didnt touch anything, wiggle anything, nothing. So I pulled it out of the garage and it did the power flicker thing and then the rpms jumped up to 1500 and held there at idle. No clue whats going on here, any ideas on what to look at??
 
jaystcb

jaystcb

Sy 0902, 92Ty 0909
Re: intermittent loss of power

Check the plastic "U" shaped vacuum line that is on the front/ bottom of your intake. Below the Throttle body linkage. I had that one fall off once and cause some of the symptoms that you are getting.
 
D

Damian

Member
Re: intermittent loss of power

It's not something that happens all the time. I started her up today and it was fine until I hit over 2200rpms. I unplugged the knock sensor and just plugged in a new one just to see what happens. The truck went over 2200rpms with no problems but I got a code for ESC. So I'm going to put this new knock sensor in and then take out the pickup and take it in and get a new one.
 
Don W.

Don W.

Stab it and steer it
Re: intermittent loss of power

Damian said:
I unplugged the knock sensor and just plugged in a new one just to see what happens.
Click to expand...

I'd be careful doing this. Our knock sensor has a specific torque in the manual. I'm no engineer here but does -not- tightening the knock sensor to its correct torque make it more or less sensitive?:roll:

To me everything you say indicates an electrical issue. Hot or ground if one is haywire you're gonna get issues. Can you post a log?
 
D

Damian

Member
Re: intermittent loss of power

IMO, not torquing it to spec would result in it picking up more noise. That's my opinion. I've changed oût the knock sensor a couple times already so it's more of a hassle to me now.

To me, if it had a short somewhere, I wouldn't think it would only ground out at a certain rpm. The TPS works properly as per DM shows. It also shows zero knock when this happens so that's why I went that direction. My tach has always done a "flutter" ever since I bought. Talking to Jason, I'm wondering if it has something to do with my distributor or it's related components.

I tried to put up a DM log but it kept saying invalid file.
 
Don W.

Don W.

Stab it and steer it
Re: intermittent loss of power

Damian said:
IMO, not torquing it to spec would result in it picking up more noise. That's my opinion. I've changed oût the knock sensor a couple times already so it's more of a hassle to me now.

To me, if it had a short somewhere, I wouldn't think it would only ground out at a certain rpm. The TPS works properly as per DM shows. It also shows zero knock when this happens so that's why I went that direction. My tach has always done a "flutter" ever since I bought. Talking to Jason, I'm wondering if it has something to do with my distributor or it's related components.

I tried to put up a DM log but it kept saying invalid file.
Click to expand...

Funny, my thought that leaving the knock sensor "under torqued" would make it less sensitive.:roll:

Sending PM on the DM file
 
dgoodhue

dgoodhue

BuSTeD 4.3
Re: intermittent loss of power

I am pretty sure over tightening it, makes it overly sensitive. I randomly tightened my knock sensor for my 86 Corvette and it pulled timing, I assume that I over tightened it, because the torque spec is only 14 ft-lbs. I did a quick google search and that seem to confirm that.
 
Don W.

Don W.

Stab it and steer it
Re: intermittent loss of power

dgoodhue said:
I am pretty sure over tightening it, makes it overly sensitive. I randomly tightened my knock sensor for my 86 Corvette and it pulled timing, I assume that I over tightened it, because the torque spec is only 14 ft-lbs. I did a quick google search and that seem to confirm that.
Click to expand...

Agreed. I just said it the other way around. I usually do things backwards anyway...:)
 
D

Damian

Member
Re: intermittent loss of power

I just figured if it's loose, it might move around. Last time I installed one, I wrapped the threads with Teflon tape.

Don, I'll send you an email tomorrow. Thanks in advance!
 
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