Driveability issues

[7M4EVR]

^ooh goody..this is going to get even better lol

I actually have the exact same thing in my idle, but I have always just assumed it had something to do with one of these things:

small vacuum leak, timing, worn ignition wires, plugs, etc., injector imbalance, hacked fuel system, poorly setup lex afm mod, cylinder imbalance, etc.

 

[Grandavi]

yeah, originally I thought so to, but after talking with Reg Reimer he explained that the engineers put a code in the ECU to do the little bup (you can hear it in the exhaust best) as a diagnostic. The ecu expects to see it. It isn't really a misfire and you can only barely discern it. But if you know its there, you can hear it. You can tell its not a misfire by its timing. Its like the engine turns a 50-60 times.. then bup...

However.. I haven't found anywhere that discusses it.. lol.

 

[3p141592654]

There is no such code that I have found, and I've looked at a lot of versions of 7M ECUs. Anything time related is especially easy to spot, because the only 'clock 'tick' in the ecu is a 4 milliseconds interrupt, so anything time related goes through that routine. There is plenty of diagnostics in the code, but that isn't one of them.

 

[IndigoMKII]

Interesting, most of the 7m owners here have this same stumble, I wonder what it could be, not to mention those in the thread I posted have the same issue.

 

[3p141592654]

Besides, Toyota QA would never sign off on a built-in 10s stumble. No way, no how. Guaranteed warranty headache.

 

[Nick M]

So, the hose and clamp issues are rectified?

 

[Chris_87_Turbo]

Yes, even found a wire coming out of the O2 sensor plug on the vehicle side that was broken outside of the connector. Car runs like a champ just still has this "bup" sound at idle. Complete new plugs, wires and fuel system treatment O2 reading look great, timing is correct, and all injectors are getting the same readings so everything seems to be in proper tune. I meant to post back sooner but with finals coming up and getting ready for the holidays with the kids the old lady has been keeping me hopping. Apparently I'm the only one who can co-ordinate with the 2 families.

Chris

 

[Grandavi]

The bup would be found in the idle control portion of the ECU (it only happens during idle), but again, I cant back that up with solid evidence, so I dislike talking about it.. lol.

 

[3p141592654]

Well, the idle control has many sections. It is obviously not present in the ISCV driver, since that could not disrupt fuel anyway. The idle ignition control is focused on real time idle stabilization through ignition timing adjustment at the cylinder level. Besides, cutting ignition would be an emissions disaster. The fuel cut control is all centralized to a single fuel cut matrix. There is no provision for an idle based fuel cut. I have been through that code with a fine tooth comb for several versions of ECU software. Besides, my car has no such deficiency at idle so this theory that they all do it is not true!

 

[Grandavi]

I'll hammer Reg on that when I go talk to him about my stand alone. See if he can explain it to me better. He's more engineer than mechanic so the explanations are sometimes really quick but above my pay grade... Lol

 

[Nick M]

Well, the idle control has many sections.

And bumping the pintle in and out isn't one of them.

I know what they all mean, I just don't see it on Toyota TCCS and newer. That lean miss bump on a 98 Ford Taurus maybe, not a 7M. And the lean miss on those domestics that are just like what these here are describing are a lean miss which is cylinder contribution. And cylinder contribution for one reason or another is what is wrong with their cars.

 

[Chris_87_Turbo]

I'll hammer Reg on that when I go talk to him about my stand alone. See if he can explain it to me better. He's more engineer than mechanic so the explanations are sometimes really quick but above my pay grade... Lol

It will be interesting to hear his response.

Chris