BoostAddct

Well today I finally got around to working on my own car instead of everyone else's. I wanted to do some basic maintenance on my GS since it will be my daily driver through winter and I don't want anything to fail if I can prevent it. So today I did the following;

1. Cleaned MAF and Throttle Body
2. Changed Spark Plugs, Denso IK20 (Previous Owner Used Bosch Platinums)
3. Replaced passenger upper control arm (Ball joint had some play)
4. Changed Trans Fluid, Put In Amsoil ATF (Just pan drain and fill)
5. Changed Rear Diff Fluid, Put in Amsoil Gear Lube
6. Replaced Positive Terminal and Cleaned Battery Posts

So now everything should be pretty fresh....planning on doing an oil change and another trans fluid change next week along with that new tranny dial mod guys started doing.

But here is my issue...the car still has a hesitation in the lower RPMs...When I give it decent gas (50% or more) in lower rpms (1200-3000rpm) it feels very sluggish and then all of the sudden at 3000rpm it just kicks in and has full power...I thought it was probably plugs, but now that I swapped them it still does this. Any ideas or has anyone had these same symptoms?

I was also going to replace the MAF, ECT, and O2 sensors in the near future since I have no idea if those have ever been replaced and after searching the forums it seems people have had good luck with replacing these.

BoostAddct

Oh and I also plan on replacing the fuel sock/filter thing as well.

1QWKGS4

iTrader: (3)

Before you change the plugs, Add a Can of Sea-foam in you Gas tank.. Recently, I winterized my GS400 for storage, I add Sea-foam to the gas as a stabilizer and Wow did it clear up my idle issues and some hesitation I had too..

BoostAddct

Well I already changed the plugs unfortunately...but like 10 minutes before I changed them I did the Seafoam suction through the vacuum line on the intake manifold. I was going to through some in the gas too though....haven't done that yet.

eagleeye

I had some hesitation too. After changing my air filter my pedal response has returned.

BoostAddct

The air filter still looked perfect on mine....although I will be replacing that as well when I do my air box mod.

LuxuryGS3

iTrader: (12)

All GS' have the hesitation. I believe it has something to do with the drive by wire.

BoostAddct

Mine is doing more than hesitating though...it literally feels powerless below 3k and then its like I go from 10% throttle to 100%...definitely not normal. I guess I will just cross my fingers that replacing the MAF, ECT, and O2 sensors cures it...if not those I'm thinking maybe the APPS sensor could be the culprit since I've read of a few guys having that go bad too....who knows...

1QWKGS4

iTrader: (3)

Not quite, 1998-2000 (Throttle cable) and 2001-2005 (Drive-by-wire), FYI

LuxuryGS3

iTrader: (12)

Throttle cable does not 100% fix the problem though. I've tightened mine and still have hesitation, but thanks for the clarification on the years/parts.

Thought 98-05 was drive by wire, haha.

BoostAddct

I already adjusted my throttle cable as well....it didn't fix the hesitation, but it did improve response right when I touch gas pedal. From my understanding the 98-00 use a cable that goes to an electronic motor...the 01-up are complete drive by wire. That's why people have seen improvements from replacing the accelerator sensor.

GS4_Fiend

iTrader: (22)

To me it sounds like you got a bad spot in the tps. But its hard to diagnose online. If you had this problem prior, i would get the tps checked out on the lab scope. Snap the throttle and watch te waveform if theres a sudden drop in voltage, if yes replace tps and reflash them PROM. GL

BoostAddct

I haven't tested the TPS yet so I'll definitely have to check that. I hope you are right though.