7MGTE Fuel Cut at 2700rpm

[kaiser]

And I know a little about feed back based microcontroller based control systems. I am heavily leaning towards the lack of afm freq input being the problem. While the tccs is seeing the correct voltage on Ks it is not getting the input needed to adjust the injector pulse duration.

Is that a valid theory?

 

[kaiser]

New used afm installed. Identical symptoms. I will pull codes and try reseting to ign timing today again. Also will try my backup ecu. Help?

 

[kaiser]

Codes: 21,31,51

less than 1ohm measured between afm sensor and ecu on KS, VC, E2, THA and OX, HT, B+ between ox sensor and ECU.

VC = 4.99V when IGN is on and 11.8V between HT and B+ when IGN is on.

 

[IndigoMKII]

Hmm. Recalibrate TPS.

 

[kaiser]

Did that, no change.

 

[IndigoMKII]

Did that, no change.

If you recalibrated the TPS, and you still have a code 51..

 

[jetjock]

Again with the conflicting info. I thought you said before there weren't codes? While they all should be fixed the only one that'll cause your problem is 31. It's always been that way. Stop screwing around and fix it. Measure the signal at the ECU. If it's correct replace the box, although I'll be very surprised if its at fault. If the signal isn't correct repair the wiring or replace the karman sensor. None of this is rocket science.

 

[3p141592654]

If its rev limiting at 3000 rpm then there should be a code 31. Check codes again.

Yeah, 31, now there's a clue!

 

[kaiser]

If you recalibrated the TPS, and you still have a code 51..

AC Is deleted, couldn't that also cause 51? Also I am not running a NSW.

Again with the conflicting info. I thought you said before there weren't codes? While they all should be fixed the only one that'll cause your problem is 31. It's always been that way. Stop screwing around and fix it. Measure the signal at the ECU. If it's correct replace the box, although I'll be very surprised if its at fault. If the signal isn't correct repair the wiring or replace the karman sensor. None of this is rocket science.

Wiring comes through as less then 1 ohm between sensor and ecu.
I am on my third afm sensor.
I do not have access to a Ocilliscope off hand to measure frequency.

Yeah, 31, now there's a clue!

Yeah bad afm, except wiring is fine and I am on my third afm.

 

[kaiser]

Also, since I reset the timing the idle is much better. Still idles at 10.4 afr.

Could this maybe be a bad TPS?

 

[3p141592654]

How do you expect it to idle properly without an air flow signal? It is currently operating in limp mode with a code 31, fuel cut at 3000 rpm, and a 2 point fuel map. If you want it to ever run properly you need to fix code 31.

 

[jetjock]

Yeah bad afm, except wiring is fine and I am on my third afm.

All that does is prove the box is smarter than you are.

 

[Nick M]

I do not have access to a Ocilliscope off hand to measure frequency.

You don't need a scope to measure Hz. Even a low dollar (relatively) Fluke 115 will accurately show you the airflow meter signal.

 

[suprarx7nut]

If you're on AFM 3 and you still have a code 31.... Perhaps the problem is with the wiring back to the ecu. 31 generally signifies an open or a short.

Are you positive there are no shorts within the AFM or to ground on all the AFM wiring?

Sent from my Galaxy Nexus using Tapatalk 2

 

[kaiser]

If you're on AFM 3 and you still have a code 31.... Perhaps the problem is with the wiring back to the ecu. 31 generally signifies an open or a short.

Are you positive there are no shorts within the AFM or to ground on all the AFM wiring?

Sent from my Galaxy Nexus using Tapatalk 2

Figured it out. Wiring to the ECU was fine as well as wiring to ECU GND but the wire to the IM ground was ringing in at >1ohm. I ran new wire and voila!

So Problem solved thanks SM!

And Jet Jock, your are less then useful. Your behavior is disappointing even by SF standards. If you spent more time providing valid input rather then quirky semi useful one liners this may have been solved easier.

 

[supraguy@aol]

Lol.
You started this thread on the 31st of May; waited till the 28th of June to mention the ecu's fault codes.
Information is a two-way street, or conversely, garbage in = garbage out.

Glad you got it fixed.

 

[kaiser]

Lol.
You started this thread on the 31st of May; waited till the 28th of June to mention the ecu's fault codes.
Information is a two-way street, or conversely, garbage in = garbage out.

Glad you got it fixed.

Lol, True, took me a little while to figure out how to pull the codes when there is no dash cel hooked up on my truck.

Plus i could only work on it on the weekend because I work out of town.

 

[jetjock]

...And Jet Jock, your are less then useful. Your behavior is disappointing even by SF standards. If you spent more time providing valid input rather then quirky semi useful one liners this may have been solved easier.

Lol. Yeah, easier. At least one of us is dazzled by your technical prowess. Buh-bye!

 

[OfnaRcR4]

And Jet Jock, your are less then useful. Your behavior is disappointing even by SF standards. If you spent more time providing valid input rather then quirky semi useful one liners this may have been solved easier.

Bansuit on!

I have to agree and I haven't even really read this thread. That's the last time I will comment on this matter.

 

[suprarx7nut]

Bansuit on!

I have to agree and I haven't even really read this thread. That's the last time I will comment on this matter.

I think he forgets what it's like to be a beginner or really anything but a "good" home mechanic.
There are plenty of dumb people and questions, but there are also plain old newbs who just need some guidance. Not everyone is a diagnostician around here and that's OK.

Part of the point of the forums is to help the uneducated become educated.

Hopefully the op learned the importance of connecting a check engine light. Even if he doesn't somebody else might read this and learn from it.

Sent from my Galaxy Nexus using Tapatalk 2