sc-driver

iTrader: (7)

So i was out last night and the car was driving like a champ . I'm cruising at like 40mph and decided to WOT it. i felt the car downshift to second.....then it kinda struggled and took off. i let go and tried it again. this time it barely accelerated.

I pull into a parking lot and the car sounds like a tractor at idle. I decide to just limp the car back home. it had a rough high idle and a tough time accelerating.

the thing that troubles me is that there are no CEL's.

i've been doing my research and tested my ignition coils. both worked fine. air filter is clean and fuel filter was changed last year.

• So i'm thinking that the tps sensor went out. The wire for the tps sensor was on too tight and pulling the wire slightly. I loosened it to the proper spot.
  
• Maybe the MAF has finally gone out. It was giving me some problems 3 months ago but a good cleaning fixed it up.
  
• The fuel pump ecu died or maybe the fuel filter got clogged.

any suggestions you guys? im using my mom's van to get around.
thanks

2jzlex

iTrader: (3)

Check those plugs homie.

sc-driver

iTrader: (7)

spark plugs were changed less than 15,000 miles ago
I'm going to check voltages on the maf, tps and wires and see if I can find out anything.

Anyone else have any suggestions?

Thanks

2jzlex

iTrader: (3)

.......................................................

You need to pull the spark plugs and they will tell you what's happening.......

You don't just start checking random things. When you're diagnosing problems, you check anything that's blatantly wrong, then spark on every cylinder, then fuel on every cylinder (or vice versa), timing, then u start checking voltages and process of elimination. You're doing this backwards.

sc-driver

iTrader: (7)

I'm not really checking random things. I narrowed down the possible culprits by searching other threads related to "hesitation", "power loss", "sudden power loss", "sputtering", "slow acceleration"...and so on.

My search led me to see that the solution to most of these cases was an ignition coil. I checked the ignition coils and both work fine. So the next thing to check was the MAF. Checking the voltage with a multimeter referring to the repair manual, it checked out okay.

Fuel filter also came up on my search, but I had it changed less than a year ago. And it wouldn't explain why my idle is a bit high.

Lastly, the throttle position sensor seemed to be a cause for hesitation as well. My gut says its this since the sudden power loss occurred when I stepped on the gas and the car downshifted.

I can see what you're saying how I'm checking random things, but I can assure you I'm not. From my 4 hours of searching on club lexus, I am going through a process of elimination from what previous members have gone through and solved.

I did what you suggested and took out the plugs, they look good. They are all getting spark and confirmed that they are all getting fuel too.

I just want to see what other members have experienced and see if they can relate and if they solved this problem already.

Still, I really appreciate any help since this is my daily driver.

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Update: Took the car for a spin. The power loss seems to be only on the low side. When I step on the gas, it hesitates, sputters and then accelerates normally. Once on the upper rpm the car picks up and PULLS.

There is a high idle at warm operating temperature (~900rpm. normal is 600rpm) and low idle at stone cold engine (~1000rpm vs 1250rpm normal)

Still no CEL's

over40driv

Ive thrown my 2 cents in before, my car is well tuned, new cat. conv., has a hesitation in high gear between 1200-1600, perf. idle, sometimes you pull away from a stop and it will bog, sometimes runs perf. Id like to try a new ECU, or get my injectors cleaned and rebuilt.

sc-driver

iTrader: (7)

driving casually today and CEL p0171 came up System Too Lean - Bank 1.

It's driving better now. It'll hesitate, and sputter when I step on the gas to make it downshift or take off. Warm idle is fine now, but cold idle is still really low.

Car really picks up and pulls hard at a higher rpm.

over40driv

Dude I just checked my current MPG , 23. Thats with the AC on 75% and not light footing it. If I could get the bug out I think it would do better. My dads telling me I should clean the TB guess it couldnt hurt. What do you think about getting the injectors rebuilt, SC? Also didnt you get a new ECU or were you just giving a link about a new ECU?

sc-driver

iTrader: (7)

It couldn't hurt to get the injectors rebuilt or replaced. Is your car throwing any codes? You could try the 12v fuel pump mod and see if it changes anything.

Yup, I got another ecu. It just bugs me how this hesitation/power loss happened so suddenly. I'm going to hook up my old one and see how it reacts.

So far, I think I can narrow down the problems to the MAF, TPS Sensor, Fuel Pump ECU, clogging fuel filter, and someone mentioned that it could be a clogging cat.

-David

over40driv

I have no CEL, also have a new cat. conv., didnt seem to make that big of a diff. Check out the new thead about strange prob. dirty injectors.

AEMxRACER

Whats a CEL? dont hate- lol

also, my 93 isnt starting.....took it to the shop, theyve been testing everything, the plugs are in good condition but not sparking, electrical problem? theyve been testing all the wiring but cant seem to find a problem...has anyone had experience with the car just refusing to start? it cranks but wont turnover

sc-driver

iTrader: (7)

CEL = Check Engine Light
Seems like your fuel pump ecu went out. Search how to do the 12V Fuel Mod. Should fix your problem.



On a side note, I drove the car on the freeway today and as I stepped on the gas to pass someone, the lean CEL code went away. It came back on later on. I'm going to put in some fuel injector cleaner and see where it goes.

bangdangvn

does system lean indicate o2 sensor like the obd1 sc300? I had the check engine light on and I pulled it as code 25, system lean and i looked it up as bad o2 sensors(front). hope you get this solve because mine is having the same issues with boggin at 40mph and such. already swap the tps sensor, clean TB, new cap/rotor, etc.

AEMxRACER

Thanks SC-Driver, I shall try that in the morning

89MA70

iTrader: (2)

i'm having the same problems right now. Pulled the plugs today and they are pitch black. havent changed out the fuel filter yet tho. these plugs are brand new and i put them in last week.

idle is low when cold and normal temp. sometimes the idles goes up and down from like 200/300 rpm upto 2500rpm. and it blows smoke out the mufflers color of smoke is white/maybe tint of blue. smells like gas.

any ideas? its got spark but very lil..

update. got the coil tested and its kinda weak. i'm change it out and see what it does. if that dont work then i'ma do a compression test.