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DYNO my Stock 1994 LS400

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Old 12-30-13, 04:32 PM   #1
stephen18
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Question DYNO my Stock 1994 LS400

Interesting results... discuss!

HP number was flat..though i feel like it should've increased with the RPMs

193 ftlbs tq @ 3550
144 HP @ 5100

OEM air filter with OEM intake / exhaust. tuneup less than 25k ago, incl timing belt
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DYNO my Stock 1994 LS400-imag0818.jpg  
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Old 12-30-13, 05:21 PM   #2
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This doesn't seem right to me. My 93 basically stock put down 194hp and 197tq. The only things had done to it at the time were a cone filter and exhaust work with stock manifolds. It also had a bad miss and no second gear on the dyno. I don't have a print out of mine but your hp numbers seem really low to me.
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Old 12-30-13, 05:30 PM   #3
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I think I read your thread with your dyno numbers....

I thought my hp was very low. Plus, I had always thought my car was slower than it should be, its been kicking my ***.. and my wallets lol
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Old 12-30-13, 05:39 PM   #4
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Well your tq numbers are about right. Do you have any issues with the car? It could be multiple things (ECU, tune-up, ECT....etc)
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Old 12-30-13, 05:54 PM   #5
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ECU was rebuilt by me
ECT temp sensor is new OEM
plugs, wires, caps, coils are less than 25k miles
Ignitors and coils were swapped with a friends LS400
Crank and both cam position sensors test in spec
throttle body, intake, and injectors were cleaned by hand/solvent
fuel pump and filter new

TPS does test out of spec.. higer resistance, but smooth transition between idle and WOT. IDL switch works and adjusted right. just very expensive from Lexus so im hesitant on that one

the PO drove the car on 4cyl and melted the cats.. theyre replaced now but there may be pieces in the mufflers
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Old 12-30-13, 06:34 PM   #6
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what kind of dyno is this? what correction factor was applied? What gear were you in?


USoff- having no 2nd gear wouldn't make a difference, dyno pulls are supposed to be done in whatever gear is closest to 1:1 anyways, usually 3rd or 4th.
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Old 12-30-13, 06:44 PM   #7
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it was a dynocom, supposedly reads like a mustang dyno
3rd gear
CF .98

many specs were at the bottom of the page
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Old 12-30-13, 07:09 PM   #8
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PD - I know about the 1:1. My car was done in 3rd gear also. I was just stating all of the issues that my car had at the time and still put down decent numbers. I wonder if it had something to do with the dyno itself?
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Old 12-31-13, 01:14 AM   #9
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I'm pretty sure they calculated the correction factor wrong (but not 100% as i'm not sure of actual vapor pressure where you live when it was done) using humidity instead of vapor pressure.

dynocoms usually read higher than mustang (heartbreak) dynos and others by a solid 5-15% depending on the setup, so either you dynoed poorly or something serious is wrong.
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Old 12-31-13, 05:44 AM   #10
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well if it helps any it was ~75* and 110 feet above sea level.

I'm not as concerned with the numbers as much as the power curve. The torque dropping off so soon and drastically is kinda scary. we did several runs and they were pretty similar.

I need to check compression to make sure all is well internally, then recheck valve timing, and I guess drop the $$ for a TPS.
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Old 12-31-13, 03:18 PM   #11
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falling on it's face like that is usually a sign of a major restriction somewhere; plugged cat, crushed exhaust pipe, broken muffler, etc.
if you have done any exhaust work, it can also be from going too big on your piping.
Could also be an improperly installed timing belt.

i don't know the state of your car but if you have not done it, a MAJOR tune up is in order.

the elevation is not going to matter that much with your dyno, maybe 2% max.
the dyno setup and correction factors are probably playing into the low numbers but to fall on it's face like that after 3500rpm is a bit concerning.
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Old 12-31-13, 05:50 PM   #12
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Quote:
Originally Posted by stephen18 View Post
ECU was rebuilt by me
How did you rebuild it? Did you use good capacitors?

Irregular capacitors can't eliminate ripples/noise enough and they cause malfunctions of processors especially at higher rpm and at lower temperature.
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Old 01-01-14, 09:22 AM   #13
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Go and drive another car of the similar generation to compare it against, that don't look right at all!
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Old 01-01-14, 05:18 PM   #14
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Quote:
Originally Posted by Yamae View Post
How did you rebuild it? Did you use good capacitors?

Irregular capacitors can't eliminate ripples/noise enough and they cause malfunctions of processors especially at higher rpm and at lower temperature.
I used the recommended caps from Digikey, and soldered them in very close to the board, and on both sides.

I unbolted the exhaust from behind the cats yesterday and drove it about ~100 miles, with no noticeable increase in power, although VERY loud, so you KNOW I bolted it right back up when I got home yesterday.
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Old 01-01-14, 06:50 PM   #15
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The exhaust was the first thing that came to mind. Unbolting it was a good test and surprising that it was not the problem.

So, what is the history on the car?

One thing I have seen on some cars is excessive (dramatic) carbon junk build up in the intake ports and on the intake valves. Usually fuel related. Hard to check without pulling the intake but would have decent performance at low RPMs and a similar power curve to yours... flat.

How many miles are on the car?
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