92Q Engine Cutting out and trans shift issues

[pbedrosi]

I recently replaced my 92Q trans with a unit from 94. Since the trans swap I'm having strange driveability issues. Not sure if they are related.

Trans issues out of the way first.....it won't shift into upper gears until warm. Usually I need to get the engine over 3 grand and let off the accelerator before the trans shifts (hard). Could be gunk in the valve body, or worn seal causing pressure drop when cold. I may put in some trans cleaner and flush out the system. Also, 99% of the time at ignition on I get "trans malfunction" on my trip LCD. I'm still trying to get a hold of 94 TCU just to be sure these are not TCU related. Forgot to add, it won't downshift at full throttle..needs to be manually shifted.

Regarding the engine.....Couple of weeks ago....- Engine idle in park (engine hot) RPM's surged to 2,000rpm for about 10 seconds. Shortly after it did it again. - Cold start RPM is 2,000, and stays up there for over a minute- Highway driving slight pressure relief on the accelerator pedal drops RPM's, need to keep pressure on the accel Pedal to keep from surging (500rpm).

Tonight I felt it even worse in full throttle.......I feel surge at stop light, I mash the throttle wide open (shifter in low) the car accelerates hard than falls flat on its face, very bad, 2,000 RPM drop as if fuel was cut, then on again, off again...all while I have my foot buried to the floor. Felt like the shock was going to rip the driveline...I Get on the highway and if I don't keep any pressure on the accelerator pedal (slight downwards grade) it drops RPM's, it takes some throttle to get it back up again but very abrupt, almost like severe TQ lockup engaging and disengaging.

Car only has 76k miles on it, ran amazingly nice before the transmission failure. The previus owner spent $3k in fuel injector service. Don't know what the freak is going on. Could it be bad 02 sensors? coils? TPS?

[pbedrosi]

Forgot to add....my ck engine light flickers on and off sometimes. Mostly it is off. During the major surge episode above it stayed lit.

[Q45tech]

15 year old car means more than low mileage.

76k normally shows up at 6-7 years, now seems to be your 2 @ $6,000 years which usually were around 120-150k and years ago for most 1992.

You need to get correct TCU before you fry the AT from 2nd gear starts especially with the 94 reduced gearing in 1st and 2nd.

The dealer or other expert will be happy to diagnose and give you a page long itemized list.

Check fuel pressure and MAF also IAC............by now all the connections are rotten and harness connectors need replacing.

[goody90q45]

I recently replaced my 92Q trans with a unit from 94. Since the trans swap I'm having strange driveability issues. Not sure if they are related. ....I'm still trying to get a hold of 94 TCU just to be sure these are not TCU related.

The 92 TCU with a 94 transmission may or may not be causing your problems but you definately need to replace it with a 94-95 TCU to make sure.

PopPop has them for sale for $85 shipped. I got one last month for a friend's 90Q and it works great. It's a DIY- Very simple to install.

zerothread/209197

[pbedrosi]

I'll drop PopPop a line. I was hoping to get a TCU under $85. I'm going to clean out the MAF just to make sure. I'm sure it needs cleaning regardless.

I also bought some sea foam brand trans cleaner. I'm going to try 1/2 the bottle and drive around for couple of days and have the trans fluid flushed.

I'll check the connectors but I doubt they are rotted out. Car was well maintained in So Cal and garage stored. Underside looks brand new. The hills of Palos Verdes took it's toll on the trans though.

In the meantime I'm going to rebuild the original 92 trans just in case.

[pbedrosi]

I think this may be it....sounds similar to my issue...zerothread?id=135741

One final question.....have you guys used universal O2 sensors? Bosch direct replacement is $95....Borg Warner 3-wire universal is $18.

[maxnix]

I also bought some sea foam brand trans cleaner. I'm going to try 1/2 the bottle and drive around for couple of days and have the trans fluid flushed.

In the meantime I'm going to rebuild the original 92 trans just in case.

DON"T!! Use BG transmission cleaner properly at time of mechanical fluid exchange, pan drop, filter replacement.

If you are not a professional that rehabilitates hundreds of these annually with OEM remanufactured parts, don't even try to match what you get with a Nissan remanufactured one.

[pbedrosi]

why not sea foam over BG? where do you get BG stuff...

During the trans swap I had the guys install new filter and new fluid. Not planning on replacing filter again...

[Q45tech]

http://www.seafoamsales.com/pdf/MSDS_SFTT_US.pdf

If one bothers to study the chemistry of Sea Foam you see the snake oil doesn't contain anything but oil, naptha, and Isopropyl Alcohol in varying percentages depending on the use label

The key to understanding is that none of components are carcogenic, thus do little and are safe to sell/ship to general public in any quantity..............kind of like over the counter vs scheduled drugs.

If you can buy it at a discount automotive store chances are it is marginally effective..........requires constant reapplication.

Some of the Stop Leak products are exceptions.

[maxnix]

where do you get BG stuff...

http://www.bgfindashop.com

[pbedrosi]

Last week I removed the MAF and gave it a good clean using CRC cleaner. The connector is tight, so I just cleaned it up and added some proper grease. I checked injector resistance and all were within spec. I checked crank position sensor and it was slightly out of range, 566k ohms I think. I adjusted the ACC to get the idle RPM down, especially cold start.

After the cleaning and checking the results were the same. About 1 in 5 times I drive the car I get the same hesitation at part throttle, followed by the engine light. I can tell it's "1" of 5 times when the cold start RPM's are above 2k and it does not settle at all until engine is fully warm. Normal startup is 1,500 RPM. In either case, until the car is warmed up it has a tough time keeping smooth idle.

Don't know what to check next. I'll have to read the service manual about idle adjustment. Even though I messed with the ACC, I don't think it's at the right setting (didn't count the number of turns).

As for the BG stuff...I bid on a couple of cans of that stuff. From the link above I found a bunch of auto dealers in the area with BG products. Not sure if these dealers are selling the BG product or offering services using BG products.