Manual swap with ECM

[dleroy43]

For anyone with an ECM controlled chevy who swaped from auto to manual trans, What id you do with the wires. Do I leave them open or ground them???

thanks

 

[dyeager535]

We dealing with an electronically controlled trans (4L60E/4L80E) or 350/400/700R4?

 

[bp71k5]

I just cut the convertor lockup wires out and then had it deleted in the chip.

 

[dyeager535]

With an ECM, you shouldn't have to do anything to keep it running ok on an auto to manual swap, AFAIK there are no codes thrown in the early TBI setups if the TCC or a pressure switch fails.

Of course, timing and fueling strategies are completely different with a converter vs. a clutch, but normally it's not something that makes it run terrible, so with early TBI, you SHOULD be able to run an auto PROM with manual trans without major problems. A manual trans PROM has significant changes in those regards, so it isn't running "right", but it will run ok. Likely missing some performance and more than likely losing some driveability with shifting, idle, etc.

 

[82355]

I swapped an SM465 into my 1988 V10 Suburban in place of a TH700R4 and did nothing, it runs better.

Martin

 

[bp71k5]

I'll clarify that mine ran fine with the stock auto chip and the wires not connected to anything. I didn't even ground the park/neutral switch. The chip was needed for my engine modifications so I had the other stuff removed since I was getting a chip anyway.

 

[dyeager535]

Look at the timing maps (and everything else that deals with idle, timing and fueling) for same stock setup except manual vs. auto, and you'll see what I mean. I thought two had been posted before, but I can't find if so, and can't pull up a 1227747 timing map auto vs. manual to post.

Just pointing out that there is a HUGE difference in engine load with a torque converter vs. clutch in all types of engine conditions, idling, WOT, etc. It's intuitive that an automatic trans setup in drive, at a stop, is a whole lot different than a clutch in neutral, and at WOT or cruise with no TCC.

I take great pains to emphasize that the differences may not be readily noticed. But they are indeed there, and are more than likely costing HP, driveability, and mileage to at least a minor extent.

 

[cabledawg]

Yeah I've done this on an 88 R10 Burb and a 90 V1500 Burb and neither one really has any issues. Sometimes, the SES light kicks on under hard acceleration or engine braking, but otherwise, nothing.

 

[80' 427]

Look at the timing maps (and everything else that deals with idle, timing and fueling) for same stock setup except manual vs. auto, and you'll see what I mean. I thought two had been posted before, but I can't find if so, and can't pull up a 1227747 timing map auto vs. manual to post.

Just pointing out that there is a HUGE difference in engine load with a torque converter vs. clutch in all types of engine conditions, idling, WOT, etc. It's intuitive that an automatic trans setup in drive, at a stop, is a whole lot different than a clutch in neutral, and at WOT or cruise with no TCC.

I take great pains to emphasize that the differences may not be readily noticed. But they are indeed there, and are more than likely costing HP, driveability, and mileage to at least a minor extent.

Yep I am sure 82355's 305 headed, hot cammed, 355 will be so much happier. Stock for stock yes. Modified it doesn't make much difference. Turn the stock timing to 8 degrees and go.

 

[dyeager535]

Modified it doesn't make much difference. Turn the stock timing to 8 degrees and go.

Modified exacerbates any problems that already exist.

8* of additional base timing? I'm into the knock sensor at 0* base and at heavier throttle, the knock sensor is taking out 8* of timing, with "just" a head/intake change over stock!

 

[80' 427]

Modified exacerbates any problems that already exist.

8* of additional base timing? I'm into the knock sensor at 0* base and at heavier throttle, the knock sensor is taking out 8* of timing, with "just" a head/intake change over stock!

See you missed it again. His is a missmatched pos. It starts to make power about the time the heads run out of air. I had a 90 with 8 degrees of advance never had spark retard. You ever try topend engine cleaner?

 

[dyeager535]

See you missed it again. His is a missmatched pos. It starts to make power about the time the heads run out of air. I had a 90 with 8 degrees of advance never had spark retard. You ever try topend engine cleaner?

Have never run top engine cleaner, pulled the heads off though, and almost as clean as when I installed them.

Did you datalog/monitor the vehicle when it had 8* of advance? I never hear nor feel it, and would never know, except the datalog doesn't lie...I'm costing myself performance by not tuning it from stock settings.

 

[dleroy43]

I put a Jet power chip in my burb (for an auto) and it worked fine, but it was slow up hills . I still have the stock manual chip from the burb so Ill just throw that in and cut the wires.

Thanks

 

[dyeager535]

Dump the Jet chip.

Jet and hypertech (and I'm sure others) advance the timing in the chip, and that's essentially it. The recommendation of a cooler t-stat is to prevent the detonation that is likely to happen at higher chamber temps.

I'm betting thats the reason it was slow up hills...the ECM is retarding timing based on knock.

Have your old stock chip for the auto? I'd swap either chip (stock or manual) for the Jet and see how it performs comparatively.

 

[fmstruck]

^You're thinking too much.

 

[80' 427]

Have never run top engine cleaner, pulled the heads off though, and almost as clean as when I installed them.

Did you datalog/monitor the vehicle when it had 8* of advance? I never hear nor feel it, and would never know, except the datalog doesn't lie...I'm costing myself performance by not tuning it from stock settings.

dataloged it no knock counts. Did have use a 180 thermostat so that may have helped.

 

[82355]

I have no knock at 8* base timing. My engine runs much better with an OEM chip and a manual than it ever did with an OEM chip and an auto.

Martin

 

[dyeager535]

<---Watched others make mistakes.

^You're thinking too much.

Had enough time to pull up a quick comparison. Both truck 1227747 ECM's, both 305's, top image, ARPC (this is the BCC, what GM identified the PROM calibration with) is a manual, AJUK is the auto.

Is 6* of timing difference at idle, and 7* at higher RPM's meaningful? There's almost a 10* difference at cruise RPM under various load!

BTW, there is a 2* difference in WOT spark too, so that's another 2* to add in or subtract to the above tables under heavy throttle. I'd take more screenshots, but rest assured, just about every table in there from IAC steps at idle to air/fuel ratio at startup based on coolant temp is different.

I'll say it again...will you notice these differences to the negative? Maybe, maybe not. But don't ignore the fact that auto and manuals aren't the same animal. Auto PROM with Manual trans isn't going to introduce the problems that you'd see if you tried a manual trans prom in an auto equipped vehicle, but those differences are still there.

Edit: I can't see the images where I am now, except red X's, and there appears to be more than the two I tried to link. So apologies if it looks goofy, my internet at the house is painfully slow.

 

[fmstruck]

So, the 30-100 across the top of the chart is Vehicle Speed?

 

[dyeager535]

Nope, engine load.

I'm not that "up" on the MAP setups, however that may be the kPa that the MAP sees, or it may be another way GM measured load. But it's a typical chart, left to right, low to high load.