OK, my L98 has about 160,000 miles on it, and it always ran like a top. In the past few months, I've noticed that it had to warm up a little, and the 100% perfect idle that it used to have has become a pretty good idle that stumbles at times. The car seemed to run good though. Every now and then, it hiccuped a little while cruising at a constant idle, but again, no real problem, just something I chalked up to needing a tune-up, and being a higher mileage motor.

...all this until this weekend.

I don't normally shift the 700r4 manually from 1st gear, but I wanted to romp on it a bit and have some fun. The motor just screamed up to 4000 rpm with no problem, power felt fine, and then at 4000, it stopped accelerating. I don't mean that my power band was falling off, I mean NO accelerating, all this at WOT. On top of that, the tranny took a good 3 seconds to finally shift. Now my 700 still shifts firmer than most 700 I've seen, so I don't think it's a tranny problem. I tried this again from DRIVE, and same thing. NO accelerating right at 4000 and a REALLY lazy shift. Well beyond a simple slushy A4 shift. Under about 80% percent throttle, it ran perfect. Firm quick shifts, good power. No problem. But time and time again, it just seems to stick at 4000, and in 2nd too, not just from 1st. I'm thinking that maybe the shifting is sloppy because the computer is looking for couple more RPM's before shifting gears. That would make sense, since it normally shift at WOT around....say about 4400? Sound right to you guys? Anyway....I don't think the tranny is the problem at all.

What gives? What should I check? I'm fairly familiar with all the TPI sensors, but I don't have a great understanding of what they all do, and how they effect the motor.

Anyone have a thought?

 

Try a new ignition module - they are only about $30.

 

Smiley....thanks for the info. I may give that a shot.

As for new testing this evening....

OK, It's definitely a WOT thing. Actually it was a little cooler this evening and the idle was better. I think the idle issue is unrelated to my 4000rpm problem, and is probably just in need of a tune up.

The car will run smoothly all the way up to about 4700-5000rpm while in neutral. I didn't have the cajones to push it much further but it reved right through 4000 and beyond with not so much as a hiccup. True to form, while in First or Drive, while accelerating at full throttle, it won't go past 4000. It sounds like it's trying though. It looks like the tach is bouncing between 4000 and 4100. Hard to say by the tach, but you get the idea, and it sounds like it's missing. It is NOT running smoothly at that RPM.

Wouldn't the ignition module run poorly whether it was in drive OR in neutral?

Maybe the TPS? Again, wouldn't it also run poorly in neutral?

What would be fine in neutral but not in drive? Essentially the computer wouldn't know the difference, right?

Help a brother out here guys??? I don't mind tinkering, but I need a jump off point.

 

When your motor is in neutral it is not under load like it is in Drive. Therefore, it will not need near as much power to spin it. That is why it will rev in neutral fine but not while you are in Drive. Does that make sense? Maybe someone else can explain it better....
I am having problems with my car after 4000 rpms, as well and my car will rev fine in neutral, too.
As for your problem, could be TPS, ign. module (along with any other ignition part), fuel filter/pump, etc. You really need a scanner or something to put you on the right track (just like I do). I have tried an ignition module, tested my fuel pressure, and done a few other quick tests with no luck. I will probably be taking it to the shop soon since I am getting frustrated....I will let you know if I figure anything out.

Jonathan

 

Just realized yours is a '89. Your MAF could also be faulty.
Good luck....

 

My MAF is BRAND new. Less than 10 hours.

As for the car being under load, I do understand, but hadn't thought it would make a difference. After thinking about it, it makes perfect sense.

I won't have time to do any tests anytime soon.

Lemme know what you find out.

Thanks