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Just not making enough power


Guest F14CRAZY

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Guest F14CRAZY

Hey guys. I posted this at Bonneville Club. Something's up with my coupe...

Howdy. Pretend I'm dealing with a '95 SSEi, but it's actually the supercharged LN3.

The past couple days, it seems its just not making the power it should. It's like the Reatta's being pulled by a Tech 4 or something Sad . I can step it to the floor and its just not pulling like it should. It's not like a low boost issue, but like a smaller motor's been put in, or I'm towing A TON, as in 2k pounds. It's much slower than stock. I'm having to give it a lot more gas for just a little acceleration. The transmission seems to be shifting fine. I'll try to point out what I've tried.

-I had a power steering leak which was getting on the belt at the same time. I fixed it, replaced the belt (the longer one that runs the water pump, S/C, A/C) and cleaned the pulleys. I thought maybe the S/C belt was slipping. No change.

My AC Delco plugs have about 20k miles on them, maybe a little less. I pulled them all out and they all appear to be the same and look normal. No evidence of an injector stuck open, misfire, etc.

Plug wires are about the same age. I removed all of them and checked them out. All are within like 4k-6k ohms.

I spun all the serpentine acessories by hand, and all spin freely and without noise.

I swapped in a known good ECM while transfering my memcal. No change.

I'm running an Accel coil pack. Swapped in with a known good Magnavox. No change.

Oil pressure is high/good, no abornmal noises or knocks.

No CEL or hidden codes. TPS operation is good and not very old. Crankshaft PS was replaced not too long ago, though I will be visually inspecting it.

Put it in neutral while on the freeway and the car coasts freely/normally.

Checked the fuel pressure, 38 psi key on, 32 psi or so idle. Which seems to be good as far as I know. Spikes up and settles as it normally does when revved. No gas in the regulator vacuum line. Fuel pump, screen, and filter were replaced about 12k miles ago.

Have bought smaller amounts of gas while this has been happening, so I doubt its a bad batch of gas.

Starts and idles fine. No backfires, no missing.

Seems to rev fine in park, but this may info might not help any.

Air intake/filter is reasonably clean. Made a quick run with it off, infact. No change.

MAF wires appear to be clean.

TPS is fairly new and checks out good in Diagnostic Mode (slowly depressing the gas with the engine off and voltage increases like it should. You know what I mean. No dead spots)

Catalytic converter was replaced about 25 miles ago.

Seems to lack power everywhere in its RPM range.

What do you guys suppose is wrong? Thank you.

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Guest F14CRAZY

I swapped in another good coil pack assembly, no change.

I can get to WOT, and I made sure the TPS readings are true in Diagnostic Mode. Nothing wrong there.

I'm posting on Bonneville Club. I'm thinking something either in the motor or the tranny crapped out. Even at idle in park/neutrel it "sounds" like its under load, like it's in gear with the brake pedal down. Idle RPMs seem a little slow to me as well.

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Guest Reatta1

Just guessing here, but, you mentioned changing the cat about 25 miles ago. I'd look at that to see if there is any blockage. All the symptoms of a lot of back pressure.

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Guest F14CRAZY

Sorry I don't have a vacuum reading. I still need to get around and tackle a boost/vacuum gauge.

Anyway, a Bonneville Club member said that a bad cat would only act up at high RPM, but my issue is at all RPM. You guys still think it could be the cat? If so, it's not too bad of a job for me to crawl under and sawzall it off for the time being.

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You didn't tell us when it started acting up. Was it after the cat converter change, or did you do the cat converter as a trial fix? If you did, it could be the muffler stopped up.

I would consider removing the pipes before the cat converter and running it disconnected. If it runs good, that is the problem. This is many times the case when the mechanics cannot find the poor performance problem.

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Guest F14CRAZY

It lasted 20k miles under boost, ending at 172k miles. I don't think that's bad cuz its been through a lot. Obviously would have lasted longer if it had lower miles, or was rebuilt, or was "performance" rebuilt. I didn't and don't have much faith in 4T60s.

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Guest F14CRAZY

The boost/bypass control actuator is working just like it should. As Bonneville Club pointed out, I'm building RPM just fine. I could redline it if I wanted to, but still not getting anywhere. I've driven it without boost before, and it is slower, but not nearly this slow.

If I decide to stay with the 4T60, the one to have would be an "F-7" from a Cadillac. They're built a little better for V8 power.

I'm still tossing stuff around in my head. Thrasher shoudl email me back on if there is a such thing as a 4T65-HD controller for the old ECM

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  • 3 months later...
Guest imported_Fox W.

Will the F-7 or HD versions of the transmission work as a direct replacement on a 89 Reatta?

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Guest F14CRAZY

Brian recently asked Ryan about that. It seems the F-7 is actually inferior to our current transaxles. A 4T60E could be used with a standalone controller.

The 4T60-E/HD really only has improvements to the differential for the most part, and isn't worth trying to use.

I still believe the best solution is the 6 speed manual

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Guest imported_Fox W.

Sounds good, how much $,$$$ do you want to convert mine? <img src="http://forums.aaca.org/images/graemlins/smile.gif" alt="" /> heh heh. The transmission has always been a scary thing for me because I hear that Buicks in general seem to be known for having 'weak' trannys. So far I have almost 130k and no problems, and its one of the smoothest transmissions i've ever felt. (except sometimes when I put it into reverse, it's always kinda been a bit hard when you first do that, is that normal? Mine has done it since I got it almost 4 years ago. Going into drive however can hardly be felt.)

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Guest Greg Ross

Off-Topic, but;

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"> I would consider removing the pipes before the cat converter and running it disconnected </div></div>

Had this condition once, the old stock exhaust eroded/ failed right behind the converter. What ever catalyst was in there was sure gone. Oh, car wouldn't run worth a damn. With no back pressure, for whatever reason she went into

"Limp Home Mode" Literally had to feather the pedal all the time to keep her running. Happened early New Years Eve about 100 miles from home, reached a friend who called a friend and got him to open up his Muffler Shop for me. Cut out the remains of the cat. and stubbed in straight pipe with a flare on one end and gently applied muffler clamps. Worked much better and got me home!

This was pre-S/C, straight stock 3.8L

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Guest F14CRAZY

I would say that, but some smart dudes on Bonneville Club were saying the 4T65 isn't better than the 4T60-E. I didn't research it much though

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See the Thrasher page - about 2/3 of the way down there is a grey section that shows the difference between the 4T60 and 4T65 spiders. The 4T65 is designed for higher torque.

There is a chart on the GN page that indicates little difference between the 4T60E and 4T65E but considerable difference from the 440T4/4T60.

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Back in the day, automatics were heavy and had 2 or 3 speeds (weel the original Hydro had a super granny and four speeds but a fluid coupler). 4 speed Muncie was lots better but took a lot of talent to beat a good 727. Today we have five (4+lockup) and six speed automatics that are worlds better. Think the best and fastest is a good automatic with a paddle shifter.

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Hard to beat a good moderm auto trans. Power capacity is probably somewhat of a problem in this particular case, but I know the GN guys have experimented with stick trannies and generally have gone slower as a result. These are not high revving and peaky engines. Their strength is a flat torque curve and a boosted engine just enhances that even more than the horsepower. I imagine you have seen the guy on the B'ville forum with the turbo install and a 4T80 transaxle?

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Guest F14CRAZY

It is true though. An L67 has a flat torque curve and wouldn't get much out of having more than 4 speeds.

The 4T80 project is crazy. May be too big to fit in a Reatta but would be the best automatic choice.

What I do prefer though is the more positive connection between me and the vehicle with a manual. It's nice being more involved

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Guest F14CRAZY

I was wondering the same thing. I asked Ryan about it, and he said the memcal would need to be reprogrammed for idling but otherwise doesn't seem that it would make it harder to tune.

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Guest Greg Ross

When you get to the Tuning stage be prepared for some surprises. It wouldn't seem Ryan has never done manual conversion programming, he throughly messed up my PROM. I believe there are other issues besides "idle" where the programming is concerned. I believe Padgett referred to it at the time as "Anti-Fart". With an automatic it doesn't matter whether the engine drops immediately to idle. To reduce emissions, the ECM holds the idle elevated for a duration so uncombusted fuel/ air does not exit the cylinder.

I guess where I came from the 5-Spd. is a driving style. I grew up with manual trannies and like being in touch with the driveline. Personal choice! If I were going racing that would be something entirely different.

Imagine my surprise when at speed and you put your foot on the clutch the idle hangs up at about 2000 rpm.

Once I'm back on my feet and have some time to tinker I'll be asking Scott Pearson to do some programming/ tuning for me. I think he's got the manual tranny already all figured out. I'd rather go where the experience is, if he'll take it on. Process would be a whole lot easier with him sitting in the passenger seat driving the scan tool!

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This may be just a suggestion, but it has made worlds of difference in cars Ive seen it done on.

Instructions:

1. Pull catalytic converter off vehicle.

2. Set on driveway.

3. Get big metal pole.

4. Drive pole through center of catalytic converter.

5. Repeat step 4 until nothing is left inside cat.

6. Install cat and enjoy extra HP.

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What Greg was refering to is the "Deceleration Fuel Cut Off" which doesn't. If you suddenly back off the gas, the air shuts off faster than the gas (you would think they could handle that with chronosymplastic programming)and a puff of unburnt hydrocarbons comes out the pipe. This is not good for either emissions or the catalyst.

So GM designed the IAC to open up a bit and close slowly (too slowly for most) when you take your foot off the gas. To feel what happens just get up to about 45 on a straight level road. Take you foot off the gas and then shift to neutral. Feel the difference.

Part of the problem with Greg's car was that we were doing everything by long distance and slow mail and I really do not have much spare time. The right way would have been to cobble up a "clutch in" switch & program it to defeat the DFCO. It just was not done.

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Guest Greg Ross

I do have the pair of duplicate switches including the vaccuum Cruise disable for the brake pedal, just never got inspired to install them in parallel. Biggest risk is forgetting you're in Cruise Control and putting your foot on the clutch! haven't done it yet!

Padgett, for my style of driving she's delightful.

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