No overdrive

**cm1273** · 03-23-2010, 09:31 AM

My car has always slipped in and out of overdrive rather easily and a week ago a code came on which had to do with the MAF I believe high voltage or something.....and now the car feels like it barely goes into overdrive you wouldn't be able to tell it was in 4th unless you downshifted into 3rd and you can feel it a little bit....the tranny is basically new it has a 2800 stall and corvette servo..the cars computer was programmed with all the specs. any help would be great thanks! I'm trying to find where I wrote the code down at now

**joedude02** · 03-23-2010, 09:46 AM

you're probably experiencing the same thing i am. have you down shifted to 1st? is it still working? i posted a thread about it and no help yet.....................

**cm1273** · 03-23-2010, 09:59 AM

First still works fine Im going to change my O2's and see if that does anything

**Hi-Po** · 03-23-2010, 12:36 PM

Get that code pulled. On pre 2001 vehicles, if the MAF fails, it will command full line pressure on automatic transmissions. No real explanation for it has been thought off. Kinda sounds like the opposite in your case, but thought I would mention it seeing you did have some MAF code.

**cm1273** · 03-23-2010, 03:26 PM

Ok I pulled the codes and originally when this started it was one code which was p0103 but now I have three more which are P0102, P0446 and P1870 if anyone can help I would appreciate it

**Hi-Po** · 03-23-2010, 03:59 PM

Well, 1998 is a horrible year for a PCM. The worst actually. P0102/P0103 means your MAF has failed and your now in SD by default. This could be your transmission issue, from what I stated above but its more then likely revolving around the P1870.

Start by cleaning your MAF and sensor contacts with CRC Cleaner found at any parts stores. Or even better, if you have a buddy that has a known good MAF, swap them out and go for a test drive. Either way, you gotta do something about that P0102/P0103.

P1870 (Taken directly from Performabuilt/LS1.com sponsor)

PO1870 Component slipping
Generally this code is set when TCC is commanded on and either it doesn't happen or the converter clutch does not hold. It will result in high line and very harsh shifts. Generally if you have a no lockup situation and do not set this code the issue is tuning related.

Its basically a transmission component slipping. I believe the Transgo HD-2 shift kit will solve the problem. Sounds like a valve body problem. If its not a high mileage, and you haven't been driving it like this for along time, the converter clutch might still be good. There is a fix to that also, something about putting in a stiffer spring. I dont really know as I don't own a automatic, just read too much

P0446 - I would start by making sure your gas cap is tight, and in good shape. That's the least of your worries right now though.

Call Performabuilt tomorrow, they can help you get that pesky P1870 taken care of. http://www.performabuilt.com/

**cm1273** · 03-23-2010, 04:12 PM

Thanks Hi-Po when I read the codes a couple of weeks ago the only code that came up was P0103.....I only drive the car on the weekends so I've only put a couple hundred miles on it since I first read the code I went back to pulll the codes today and ran out of gas

so thats probably where the P1870 code is coming from I guess....I cleaned the MAF yesterday cleared the codes today....so we will see what happens the guy that built my transmission said that the shift kit would make it shift to hard but who knows...guess I'll get the valve body replaced.....the torque converter only has 3000 miles as well as the tranny and motor

**Hi-Po** · 03-23-2010, 04:17 PM

Originally Posted by cm1273

Thanks Hi-Po when I read the codes a couple of weeks ago the only code that came up was P0103.....I only drive the car on the weekends so I've only put a couple hundred miles on it since I first read the code I went back to pulll the codes today and ran out of gas

so thats probably where the P1870 code is coming from I guess....I cleaned the MAF yesterday cleared the codes today....so we will see what happens the guy that built my transmission said that the shift kit would make it shift to hard but who knows...guess I'll get the valve body replaced.....the torque converter only has 3000 miles as well as the tranny and motor

I kinda missed that this was a recent rebuild. I suppose clean that MAF really good, take her for a spin. Hopefully the MAF codes go away and stay away. Start there before planning on ripping the valvebody out.

Still wouldnt hurt to call Performabuilt tomorrow to discuss it with the pro's, which I am not.

**Cutlass** · 03-23-2010, 04:19 PM

With a high stall converter and no torque converter lock-up, the 3rd to 4th shift will be barely noticeable. It'll feel like a little bump with hardly any rpm change (because of the higher stall speed) Sounds like you have a TCC lockup problem...possiblly because of your other DTC problems (ie MAF)