alraqib

Hi all, I bought my daughter a '94 Altima GXE w/AT as her first car recently and as is my custom I dove right in to get a maintenance baseline. That is, I tuned it up with cap, rotor, plugs and wires. I set the timing and RPM to spec, changed the oil, filter and trans fluid and dumped in fuel system cleaner and filled up with 93 octane.
I checked the on-board trouble codes and was showing "knock sensor" and "throttle position sensor" codes. I have replaced both and am now showing no trouble codes on the system.

So, here's the problem...
While the car starts and runs fine I'm finding that when I adjust the TPS to where I get "off" at closed throttle (rotating the top of the TPS toward the front of the motor), the engine revs high when shifting to 2nd gear and more so to 3rd. This only happens when accelerating very gently, seems to shift OK when I accelerate more aggressively.
When I adjust the TPS the opposite direction (rotating TPS toward rear of motor), the idle goes up and sits between 850-950 rpms but the trans shifts perfectly.
I'm going to clean the throttle body tomorrow thinking that I may not be getting a true closed on the throttle body, but if that fails I' stumped.

Has anyone run into this? I'd really appreciate some ideas.

alraqib

Hey folks, I'm still trying to figure out the above problem, but have a few more facts that might be relevant.

I've come to find out that the motor and trans in this '94 is a actually from a '95 model. It was swapped out by the previous owner.

My question: is the TCU from a '94 programmed differently than one from a '95?

I know the model numbers are different, ETC-N53 for the '94 and ETC-N400 for the '95.
Does anyone know if this could be the cause of above shifting problem? The current TCU is flashing 1 long and 10 short, so apparently all my sensors are OK.


BTW, I sprayed carb cleaner around the intake manifold and found leaks at #3 and #4 cylinders so I replace the intake manifold gasket and while I was at it I replaced the PCV and IACV. So, the engine is running very good.

Any input?

alraqib

Hi everyone, just an update to say I got it all worked out.

I replaced the TCU with a '95 and dropped the trans pan and replaced the filter and refilled.
The filter itself wasn't too bad, but the magnets were a bit fuzzy. Cleaned it all out and refilled with about 4 1/2 quarts and now everything works great. Although nobody replied I did learn an awful lot about Altimas from this website, so thanks all...

Altima SSS

I hear removing and replacing the intake manifold isn't very easy. Was there any tricks involved in that? Sounds like you did a lot of work that all worked out well.

I take it TCU = Tranny Control Unit? Where is that unit located?

alraqib

Altima SSS, replacing the intake manifold is certainly no picnic, but definitely doable. And when it's all said and done it feels like you've rubbed your knuckles with a cheese grater.

The way I did it was first pull or disconnect all the ancillary stuff and then pull the starter and drop the collector. You can't get the collector plenum out thru the bottom, but you can move it around enough to make room to get to the lower manifold bolts.

I put it together the opposite way, dropping the collector in unattached, torqued down the manifold and then bolted on the collector.

I'd say, all told, that it took me about 8 hours, give or take.

The TCU is located under the passenger side kick panel, just in front of the door hinge. Tell you the truth, I'm not sure that replacing that had any effect on this, since all these things seem to be inter-related, but I got the part for $20 and it was easy to swap.
After I was done I reset the timing and re-adjusted the TPS and it all fell in line.

BTW, I thinks it's true about the Bosch plugs. I replaced them with NGKs and it seems to make a difference.

Cheers...