BK4293

1992 Lexus ES300 ATX

Bucking during acceleration and can't get the car over 60 without feeling like I'm riding an energy drink addicted mechanical bull on steroids...

Replaced air/fuel meter ($50 from junkyard)
Replaced ecu ($50 from junkyard)
Replaced air intake accordion ($52 from o'riellys/murrays)
Replaced iac ($55 Craigslist)
Replaced entire exhaust front pipe (both flex pipes were leaking, ($280 done at Valasquez and Sons)
Replaced throttle body gasket, cleaned the throttle body with Barrymans throttle body spray cleaner while it was connected to the intake manifold making sure to get the IAC while I was poking around in there ($6 in gasket paper from Autozone for the throttle body and IAC $7 for the Barrymans)
Replaced dog bone motor mount ($31 at Napa for the entire dog bone)
Replaced fuel filter ($19 from autozone)
Sprayed motor down with starting fluid and couldn't find another leak for the life of me (probably $100 in starting fluid since this problem started).
Not part of the problem but also replaced altenator and battery within the last two weeks ($133 for the altenator from PepBoys and the battery replaced under warranty at Autozone)

Engine feels like it misses when at idle but is decent while the motor is cold but really gets bucking when she starts warming up and I can smell gas inside the cabin. The bucking/missing gets really bad during acceleration but can still feel it somewhat when cruising or just idling.

The engine feels the same whether I go forward or reverse.

I've been doing searches on this site for weeks now and have found quite a few solutions to my problem and none of them seem to have stopped the engine from bucking.

The only codes thrown are 52 and 55 which are the two knock sensors.

jrryjms07

Check yur tps (throttle position sensor) my engine code says it needs to be replaced and bucks at acc and smells like gas too.. i just ordered mine so i wont knoe the outcome yet..

BK4293

Thanks! I'm lost because there are no codes thrown. This cars been nickle and diming me to death the last couple of months. Please keep me informed before I go out and spend another $100 on the tps....

jrryjms07

def. i just ordered mine literally earlier today so im looking about wed thurs to get it in

but its about $72 at rockauto. use 47434283920651 as a discount code. to save you 5%

BK4293

I unplugged the electrical connector from the tps and it threw the code then, is it common for the tps to go bad and not throw a code?
I also unplugged the vacuum line from my egr valve and there was absolutely no change worth mentioning....

BK4293

Any way to test the tps before I pick one up? I have a multimeter but no idea how to use it so please be gentle with me....

jrryjms07

Personally idk how to test it..:/

Maybe yu can find how to do it if yu googled it..srry not that much help bro..

LeX2K

They are very easy to test. Pins 1 and 2 will be 1-2 ohms when the TPS is closed, an open circuit for anything other than closed (meaning closed throttle). The other 2 pins are variable, about 3.5 K at idle, around 500 ohms full throttle. Note that pins 1 and 2 might be around 10-30 ohms on closed throttle, several I tested were like this, the computer will still see this as valid and work correctly.

I highly doubt your problem is being caused by the TPS however.

BK4293

Any clues as to what else could be causing my problem then?

GEORGE_JET

Have you pulled one of the spark plug wires to check how "hot" the spark looks? Also check to see if the fuel pressure regulator diaphram is intact. On older cars the regulator can tear and allow raw gas to flow thru the vac line to the intake manifold ie extremely rich mixture.

BK4293

Plugs are black from running rich. I swapped them out with whatever Autozone had in stock to see if it would make a difference and it didn't. From first glance it looks like the plastic housing on the end of the fuel rail is intact, is there anything specifically I should be looking for?


.

BK4293

I'm guessing I was looking at the wrong thing, the FPR is up front correct?
It looks fine, pulled the vacuum hose and no gas leaking from anywhere that I saw...

Would a non working EGR valve cause these symptoms and not throw a code?

ASG14

iTrader: (1)

But yet, you HAVE NOT fixed that?

GEORGE_JET

EGR is not likely to cause these symptoms, but you can disconnect it for troubleshooting purposes. Was the spark bright blue, or weak yellow. also are all the plugs fairly even black?
If all the plugs are black I would next check the coolant temp sensor. The ECM uses the coolant temp sensor to enrich the mixture when it is cold. If the snsor is giving a much lower temp signal you can get a rich mixture like you describe. Be aware that there are several coolant temp sensors, one for the ecm, one for the instrument panel gauge, one for the climate control, and I believe there is also one for the hydro-fan controller. Make sure that you measure the correct sensor.

charley240

iTrader: (6)

when i had bucking issues, it was misfire, and CEL wouldnt pop up for awhile.
i had to replace my plugs, and wires.

goodluck
Charley