Rev limiter

[PlayingWithTBI]

Can you play with idle strategy stuff? It drives me nuts that my truck refused to go to curb idle unless warm and stopped for about thirty seconds. Once it's warm, I can't understand why it doesn't take the IAC counts down to about where it was last time the desired curb idle was achieved.

All I remember doing with my EBL Flash-II is setting the idle to 750 and 800 when A/C is on. After that, I haven't had any issues. Sometimes, when I shift from drive to park it'll raise to ~950 for a couple seconds, then go back to its set point.

The later TBIs are much better. They use integral and proportional filters for idle steps.

I have played with the proportional since my WBO2 is further down the exhaust stream, in the Y pipe collector, than stock exhaust manifold. But that was to get rid of surging.

 

[PlayingWithTBI]

Are there any left that haven't been swaped to 7427?

Well, I do have a couple sitting on the shelf One even has the ZIF socket for SST 27SF512 flash chip. Yeah, they are too slow with too small tables. That's why I switched to the EBL instead of the 7427.

 

[df2x4]

Always thought jet was canned only tunes?

They do sell the handheld programmer units with the "canned tunes," but they also have DST (Dynamic Spectrum Tuner) which is a complete tuning software package similar to HPT or EFILive. AFAIK it's nearly identical to the old TunerCAT software, I think JET bought them out. Pretty sure it's the only software that will interface with the '96-'97 black boxes in these trucks.

https://jetchip.com/shop/chips-modu...formance-dynamic-spectrum-tuner-programmer-2/

 

[AuroraGirl]

Interesting. Can you play with idle strategy stuff? It drives me nuts that my truck refuses to go to curb idle unless warm and stopped for about thirty seconds. Once it's warm, I can't understand why it doesn't take the IAC counts down to about where it was last time the desired curb idle was achieved. That is of course unless it doesn't store that information. All the Ford trucks from the same era do that. They will adjust curb idle while it drives, which is to say I never notice them doing it unless I'm actively paying attention. Are later year TBI's "better" at that?

If you have a scan tool, what are your IAC counts when good idle vs bad idle, and if you do a throttle snap test on those two things, what happens

 

[AuroraGirl]

Interesting. Can you play with idle strategy stuff? It drives me nuts that my truck refuses to go to curb idle unless warm and stopped for about thirty seconds. Once it's warm, I can't understand why it doesn't take the IAC counts down to about where it was last time the desired curb idle was achieved. That is of course unless it doesn't store that information. All the Ford trucks from the same era do that. They will adjust curb idle while it drives, which is to say I never notice them doing it unless I'm actively paying attention. Are later year TBI's "better" at that?

believe me tho the fords are not good at it L OL

 

[DerekTheGreat]

All I remember doing with my EBL Flash-II is setting the idle to 750 and 800 when A/C is on. After that, I haven't had any issues. Sometimes, when I shift from drive to park it'll raise to ~950 for a couple seconds, then go back to its set point.




I have played with the proportional since my WBO2 is further down the exhaust stream, in the Y pipe collector, than stock exhaust manifold. But that was to get rid of surging.

Hmm, can you play with when it tries to go to 750RPM? What about cold idle? What is adjustable and what are the grey areas? My truck has always been consistent, it will idle at 1,200 RPM (as indicated by the tach) when super cold, 1,000 RPM when just cold or below the temp at which it goes into closed loop. Once it hits that temp and all of the conditions are met, the thing will slowly make it's way to curb idle, which seems to be about 750. If the truck was an automatic I probably wouldn't care so much, but being that it's a stick, it ends up wanting to idle around 1,700 RPM between gear changes and all that. Once it hits curb idle, it behaves normally and gear changes are easier.

The later TBIs are much better. They use integral and proportional filters for idle steps.

About what year did that happen? Is that also the faster ECM that people swap to? I might actually do the swap, if that's the case and I get a better cold to hot idle transition. The '92 truck behaved the same way as my '89. Only difference between the two mechanically was that truck was a 2WD.

 

[PlayingWithTBI]

being that it's a stick, it ends up wanting to idle around 1,700 RPM between gear changes and all that. Once it hits curb idle, it behaves normally and gear changes are easier.

Hmmm I remember the calibration for a stick has a delay built in to keep the RPMs up there for easier shifting but, yours sounds different with that. What ECM are you running?

 

[Schurkey]

That and an 048 ignition control module that takes an aggressive whack at timing advancd at higher rpm. My 91 L03 Firebird had an 048 module. My 92 G20 350 had a 369. The 048 module makes a TBI fall on its face at ~4,000 rpm in stock form.

I've heard that. Primarily on a different forum.

I have some trouble believing it, though. Numerous GM part numbers are all replaced in the aftermarket by a very small number of modules. If the GM modules played games with the timing, selling non-compatible modules would violate EPA regulations for emissions performance and CAFE performance.

I changed a module said to restrict timing (048?) for one of the modules said to not restrict timing. (369?) Couldn't tell the difference in the way my truck ran. I've wanted to run a timing comparison between the two; but never achieved the ambition.

I maintain that the timing advance difference is in the computer, not in the ignition module.

Are there any left that haven't been swaped to 7427?

My '88 K1500. Maybe I don't know what I'm missing.

 

[ralmo94]

About what year did that happen? Is that also the faster ECM that people swap to? I might actually do the swap, if that's the case and I get a better cold to hot idle transition. The '92 truck behaved the same way as my '89. Only difference between the two mechanically was that truck was a 2WD.

I believe 93 when they came out with 4l60E. Electronic trans control was added and went to a pcm. There are peramiters in the $od tunes to support 700r tcc lockup.

If you look for a 1994 k1500 that's the right one. 7427, or 6395, and another number I can't remember at the moment, all the same thing and will run the same chip. Parts stores carry them, but you would need harness connectors and a memcal, socket said memcal or buy the adapter from moats.

 

[DerekTheGreat]

I believe 93 when they came out with 4l60E. Electronic trans control was added and went to a pcm. There are peramiters in the $od tunes to support 700r tcc lockup.

If you look for a 1994 k1500 that's the right one. 7427, or 6395, and another number I can't remember at the moment, all the same thing and will run the same chip. Parts stores carry them, but you would need harness connectors and a memcal, socket said memcal or buy the adapter from moats.

I'll see what I have in my parts stash, but I'll probably need to add that to the list.

If you have a scan tool, what are your IAC counts when good idle vs bad idle, and if you do a throttle snap test on those two things, what happens

I haven't checked in awhile. It's not a "bad" idle, its just what GM programmed the thing to do. Been tolerant of it for years, but every now and again I get irritated by it and miss how smoothly I could shift the Fords. Any throttle input will cause the ECM to command higher IAC counts, how much so depends on what gear it thinks you're trying to grab, if it's hot or cold and if the idle has come down or not yet. If it goes into "stall" mode it's even wonkier (idles real high) until it regains it's bearings & feels it isn't going to stall.

believe me tho the fords are not good at it L OL

I'll proudly drive either rig, but in the drivability category and in my experience, Fords are. I wouldn't mention them if I didn't think they did that better. Now, maybe its the difference between port fuel injection and throttle body injection, but I absolutely loved the 300 straight sixes I've had along with the 5.0 trucks. I want a 5.8 at some point, but now like the GMT400's, people want stupid money for an '88 to '97 F250/350. They all start up and quickly come down to 1000 RPM idle or less rather quickly. And if it's an automatic, you can put it in gear without having to ride the brakes to keep it from doing 20 mph+. They run smooth, the SEFI 302 in my Lincoln is silky smooth as well. Due to throttle geometry they don't snap your neck back when you touch into the throttle either. However, the Ford trucks of that era ride like chit compared to the GMT400 trucks. At least 2WD vs 2WD, which is all I can compare by actual experience. The '92 C1500 I had rode like a car, whereas every F150/250 I've had of that era rides like a tank, probably thanks to the I-beams. However, I still liked them. I'm especially fond the F-series' '87-'91 interiors, but '92 and up will let you plug a scan tool into it and stream live data. I bet the V8 Vortec equipped GMT400 stuff runs much like the Ford stuff does.

Hmmm I remember the calibration for a stick has a delay built in to keep the RPMs up there for easier shifting but, yours sounds different with that. What ECM are you running?

A 77.. something. I'll have to get back to you on that. I've never actually had to pull the ECM out, yet.