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Finding where shift hesitation is in scan/tune

C

cemtex

New member
I started using the HPT I got last week and have been currently working on LTFT. The issue I have though is I have an intermittent shifting issue which I do not believe is hardware related with the transmisson as the shifts are firm and there is no slipping or abuse being called out during scans. The issue is that during part throttle acceleration the transmission delays the shift for about two seconds or so and lets the revs climb a bit, and then it shifts firmly (not so harsh that it is abuse though, we are talking only normal driving). It comes and goes and I can see it in the scan but I do not know how to approach it to troubleshoot or hopefully fix it. My shift points are stock with the only change being performance has been copied over to normal on part throttle shift and shift timing. I did remove torque management (only the retard timing though).

I can provide a scan if needed along with some points in time where the issue is happening. It does not look like it is torque management because I can find examples with no KR and also the TCC not being engaged at the time.
 


I think I have it figured out. If I start and stop the car after putting in a new tune, and then start driving the transmission shifting hesitation almost nearly completely goes away. It is similar to how my DHP performed on my 97 years ago (if I wrote in a new tune, and start the car the first time ALL trouble codes would show and the transmission would not command gears on time).

Are there any parameters that are not available to HPT for the transmission? It feels like the more I drive it the more the shift points and timing are correct, as if it is learning.
 
drive the car around, when it starts to act up scan it for codes engine running, do not turn it off. you could have a pending code that will erase if you turn the car off.
 
Ok will do. It is not very dramatic just annoying. It might also be called "sloppy" so to speak, just a bit sloppier than anything I had in my 97 GTP.
 
Is there anything that the transmission is learning when I drive fresh after a write?

I made a 46 minute scan today and did not have any pending codes.
 


shifts seem to be better right after a flash, then as its learns how you drive and all the slop from wear it will start to feel not so crisp.

my old used tranny had a 300 rpm slop over at the shifts, so i set them for 5800 it shifted or took the next gear at 6100. now this new tranny is also set to 5800, and it shifts at 5800 cause it new.
 
For me it has not been like that. Mine are sloppiest right after a flash (where I have a long hesitation and a firm shift and way too much a RPM dropoff for 1-2) and typically gets better after a couple subsequent drives. It also is bad if I am in traffic or in common street conditions where frequent braking and accelerating is needed. Sometimes it feels like when I come to a stop that it does not come out of second gear, and when I put on the accelerator it will hesitate and then firmly shift into first.

I had the best drive with a stock tune and the battery undone for a while when I added a new alt. line from the alt. to the fuse box. Shifts felt normal for 50 or so miles of driving and I did some near WOT runs at 4/3 gear to get it to downshift. After about that 50 miles though the hesitation came back.

I have checked with three different scanners for any pending codes and I have none. There is no slip whatsoever (with the only odd issue is every few weeks I get a really harsh stutter from a stop at acceleration, feels more like a single cylinder misfire) and with torque management off I see the shifts in my scans but no KR and spark looks normal. TCS is on while driving and I am not attempting to spin the tires or perform any harsh driving.
 
An update. The DIC will flash a service vehicle soon but I do not have any codes or a MIL light on when I use a scanner. I guess I would need a dealership level scanner to see manufacturer and transmission codes (typically with a number other than 0 right after the P).

I checked the transmission fluid level again while the motor is hot and now it smells burnt and is only slightly high. It looks like at the least the fluid and filter need to be changed so that will be a project tomorrow morning. It might fix/help the issue but if not I understand how fragile the transmission is (I blew up the transmission on my 97 GTP) so then it would be time to consider ditching the car or getting a rebuild/replacement (I personally do not see it as worth it for these cars).

The transmission temp. has been under control the entire time, staying just below ECT at 180 or so at the highest.
 
I noticed that code P1811 will not set off a light and is unchecked so I do not know if set to no MIL light is enough to log a code. I set it in my latest tune to SES on at the check box but no MIL light still.

I put in one of those transgo shift kits for 1>2 and 2>3 and I have noticed that 1>2 shift has improved greatly. It still hangs here and there though (happened on a 3>2). I also added a little more upshift line pressure so well see how that goes. Between these issues and the MPG (18-20) it looks like either a transmission overhaul or selling the car off may be in order.
 
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