Shifting issues 99 A4 Z28

[mzoomora]

Hey guys. I have a 99 A4 Z28 with blt ons and a cam. It shifts from 1st to 4th on occasion, not all the time. It also is throwing a TPS code, but I checked that and it seems okay. I logged some driving and looked at the map and tps voltage and it all looks okay. The calculated load was only at 30-40%, but I dont know what that is supposed to be or if it even matters. If I hit it off the line it will go for a little, then hit 4th and fall on its face like it isnt even accelerating anymore, then after 5-10 seconds or so it will take off again. If I manually shift I have no problems. Any help is appreciated.

[mzoomora]

Okay guys, needing some help here. I double checked the tps and it is okay. I did a data log of a short 0-50 run where I had the problem. You can see in the log where I went full throttle, and also where it says the trans is in 4th gear.Let me know what you guys think. If you want to take a look at it I can email it to you. My email is mzoomora@msn.com. Any help is appreciated.

[joecar]

I thought a 1-4 shift would have thrown a DTC, did you get any...?

[joecar]

Document ID# 57985
1999 Chevrolet Camaro
Second/Third Gear Only or First/Fourth Gears Only

Checks
Causes
1-2 Shift Solenoid Valve (367A)
Sediment is in the valves
The electrical connection is faulty
Damaged sealIt means that the 1-2 solenoid is not exhausting when turned off due to sludge/sediment build up in it's exhaust orifices, or the solenoid is always ON (either shorted to power, or stuck on).

With key-on-engine-off you could use EFILive to command the 1-2 shift solenoid on/off and listen for it clicking each time (listen carefully, open both doors, park next to a wall, or get under car with your laptop).

If you hear the solenoid click, you then have to drop the pan and pull out the 1-2 solenoid and check it's o-ring and clean out any sludge/sediment (don't use brake clean, use CRC DQ Electronic Cleaner or CRC MAF Cleaner, blow out the solenoid passages, follow by compressed air if you have it).

If you don't hear it click, then the wiring to it is shorted on or it's stuck on;
need to check it's connector using a voltmeter (drop pan, pull connector).

[joecar]

367A is the 1-2 shift solenoid (ON in 1st and 4th)
367B is the 2-3 shift solenoid (ON in 1st and 2nd)

http://img504.imageshack.us/img504/2913/valvebody15tp.png

[joecar]

Could also be 1-2 valve (366) stuck in the on position in the 1-2 valve bore;
with a pencil magnet try to move it, and if it's stuck then valve body has to be pulled.

[mzoomora]

Thanks.
I have a question though. It is intermittant, and doesnt happen if I manually shift. Does that sound like it could still be the problem? I may just take it to a trans shop.
It is giving a light- p0121 for the tps. It checks out okay though and looks good in the logs. Map looks good also. It also seem st ohold a high idle while coasting from a cruise at say about 30-40, it wil lmaintain speed by itself and if you place it in neutral while it is doing it it will stay at about 1400-1500 until you come to a complete stop almost.

[joecar]

Intermittent means that the 1-2 valve many be sticking in its bore (especially as temp. changes).

[foff667]

i had this same problem with my cam...i just had to disable the p0121 test...I would go wot and it would be in 4th by 30mph at wot. Disabled the test & all was well.

[mzoomora]

i had this same problem with my cam...i just had to disable the p0121 test...I would go wot and it would be in 4th by 30mph at wot. Disabled the test & all was well.
Cool. How do you go about disabling that test? Is that the same as removing the code? I am new to this, so I dont want to mess anything up.
Also, has anybody else done this? Just curious to hear what else people have done or if anybody else has had this problem.

[driver456]

i had this same problem with my cam...i just had to disable the p0121 test...I would go wot and it would be in 4th by 30mph at wot. Disabled the test & all was well.
P0121 is THROTTLE POSITION SENSOR 1 PERFORMANCE. Correct me if I'm wrong. .........................Paul

[mzoomora]

P0121 is THROTTLE POSITION SENSOR 1 PERFORMANCE. Correct me if I'm wrong. .........................Paul
Yes. I think it is "position not as desired" or insufficient activity. But it seems to be fine when I log it and check it.

[mzoomora]

Hey, I just looked over the tune and there is a section "TPS Vs RPM limit Lower" and it is set for 1% @ 800 rpm, and some of my idle rpm values are actually a bit higher than that. It is mostly the P/N settings, and some on the colder ranges, but it does idle higher than that at times. My desired idle in gear at normal temps is set for 850.
Do you think this might be what is setting the code?

[joecar]

i had this same problem with my cam...i just had to disable the p0121 test...I would go wot and it would be in 4th by 30mph at wot. Disabled the test & all was well.When this happened did it skip 2nd and 3rd, or did sequence thru them really quickly on the way to 4th...?

[mzoomora]

Okay. I tried something different today. I put it in D (3rd) and it shifted directly to third instead of fourth. While I was outside logging some stuff with it at idle it had a point where it was showing 2v on both the TPS and MAP at idle, and it was showing .4% for tps position for a long time also instead of just 0. This thing has me running in circles now. I had a trans shop check it out and they are saying it is not in the trans. The TPS is new also. Any help guys. Thanks.

[joecar]

Okay. I tried something different today. I put it in D (3rd) and it shifted directly to third instead of fourth. While I was outside logging some stuff with it at idle it had a point where it was showing 2v on both the TPS and MAP at idle, and it was showing .4% for tps position for a long time also instead of just 0. This thing has me running in circles now. I had a trans shop check it out and they are saying it is not in the trans. The TPS is new also. Any help guys. Thanks.That sounds like an electrical/grounding problem or a PCM problem; requires checking the TPS and MAP and their wiring using a DMM.

When you open the throttle smoothly, the TPS voltage or % should track smoothly.

With key-on-engine-off, MAP should read barometric pressure (close to 5V); with engine running, MAP should increase in response to throttle opening.

[mzoomora]

That sounds like an electrical/grounding problem or a PCM problem; requires checking the TPS and MAP and their wiring using a DMM.

When you open the throttle smoothly, the TPS voltage or % should track smoothly.

With key-on-engine-off, MAP should read barometric pressure (close to 5V); with engine running, MAP should increase in response to throttle opening.
The TPS does react smoothly, from .7-4.5 volts. The map sensor reads 4.8 volts with the engine off I think, and read barometric pressure when off. The MAP does react when the throttle is opened.
I was wondering if the .4% (and sometimes .8%) for TPS is normal at idle?
I have a spare PCM I am trying to get flashed with a stock program to see how it reacts. I dont want to do it myself and waste a PCM lock on it and have it not be the problem. I checked the voltages at the wire ends with a multimeter and they looked fine, but it is an intermittent problem.
It high idles while cruising and doesnt go down until you come to a complete stop also. I tried everything in the P0121 troubleshooting tree and I am at the point where it reccomends the PCM be replaced.
Any other ideas or suggestions are appreciated.

[mzoomora]

Also, what grounds do you think would be the culprit? I will probably just have to go through them one at a time. All the ones I visually inspected looked fine though.

[mzoomora]

Okay, I was just out there now. I had it running in park and it was going back and forth between .4 and .8% throttle. I turned off the engine and let it sit and it started showing 1.8%, I unplugged the TPS and it went to 0, when I plugged it back it it went to 20% and stayed there. When i strted the car it was at high idle and wouldnt come down.

[joecar]

Is your throttle blade sticking open (rubbing against throttle body bore, weakened return spring, ...)...?

[mzoomora]

Checked that already when I first started having these problems. Hopefully I will be able to try a different PCM soon and see what it does.

[mzoomora]

Anybody have any ideas on deleting the p0121 test and if it will solve the problem?

[ChipsByAl]

Mzoomora, disconnecting the TPS and reconnecting is not a valid test. It will see a new low voltage and consider that zero throttle angle. When you plug it back in it sees a higher voltage and thinks you have cracked open the blade. 20% TPS is high enough to add some IAC counts and not lower the engine speed to the desired idle. The PCM doesn't think the blade is shut. If you had this problem without actually disconnecting the TPS by hand, you have a PCM or wiring concern. I would look hard at the TPS connector, make sure all of the pins have not been mutilated, enlarged as to not make good connections. You also may have an intermittent wire connection at the sensor. Pull on all three wires and make sure they don't pull out of the terminal. Sometimes the vinyl casing is intact but the internal wire has broken. Also a short to ground in the 5 volt reference circuit or output of the TPS will momentarily pull the learned minimum TPS voltage to a new value which the PCM will learn as zero. This of course would not be real and once the real value comes back "short gone" it is at a higher throttle angle.
Good luck, Al

[mzoomora]

Okay. Problem SOLVED!!! I did like foff667 said and disabled the P0121 test by raising the minimum and maximum map readings to run the test from 55/65 to 75/85. Took it for about a 20 minute test drive and it shifted fine.
Thanks for the help!

[joecar]

Is this C3904 and C3905...?

[foff667]

glad to hear you got it working right :D

[mzoomora]

joecar- Yes, those were the ones I changed.

foff667- It just took me a little while to figure it out. I had the car tuned and told him what to do, but he never got it right. I started doing some searching and figured out what parameters needed to be changed- worked like a charm.