94SC4

Thanks for all the ideas. Here's an update. The fp ecu checked out fine according to the diag procedure in the shop manual. In diagnosing the fp, I discovered if you jump the +B and FP terminals on the DLC1, it puts the fp in the high speed mode full time. Unfortunately, this had no impact other than making the engine surge at lower speeds.

I love the idea on trying to drive the car with the MAF disconnected. I'll try that next.

I have the rear seat and other parts removed so I can get to the fp and ecu easily. I may try to go to a junk yard and see if they'll let me try some parts and just start swapping out things and see what happens. I figure it's got to be a fp, fp ecu, maf, or ecm. I'm still a bit frustrated with the "stealership". Although there are no codes thrown, I thought they would have some scopes or other diag equipment to hook up and see what's occuring. Anyway, I still got the car washed and the interior vacuumed for the buck fifty.

dwebb99

iTrader: (17)

they still bent you over......and always will....find a good small indy shop that works on Toyota/Lexus primarily and has a certified mechanic. Then form a good relationship with them. Believe it or not, there are some really good small indy shops with great, honest mechanics at fair prices. You do have to do your do-diligence when looking for one though. Good luck with your problem and please tell us what you find.

94SC4

Well, I did the MAF disconnect and didn't get any change.

I'm heading the junk yard this week and will try swapping the fp ecu, fp, and ecm one at a time. This is turning out to be a very tough one to figure out!

94SC4

This past week, I went to a junk yard and bought an ECU. The engine still cuts out above 5K rpm. I then picked up a fuel pump. No change to the problem.

I had an idea maybe the tranny was prematurely telling the ECU to cut back the engine. So I left it in L gear and no change to the problem. I also tried it in 2 gear with no change.

I did learn that the engine will surge at high rpms (around 4500 rpm) under light throttle as well so it seems there is something about higher rpms the engine doesn't like. Under normal driving, everything is so smooth and strong. I also tested the cam position sensors according to the shop manual and they're fine. I also unhooked the Trac control sensor and actuator to ensure the Trac system wasn't causing the issue.

Has anyone had ignitors (not the coils) go out? Do they get weak or just stop working? Next up, I'll test the crank sensor to ensure that's okay.

I'd like to simplify the engine systems as much as possible to eliminate possibilities. Can you disconnect the IAC and EGR systems without causing issues other than codes? Any other systems besides Trac and MAF that I could disconnect to simplify?

I'm out of ideas .... if anyone has had something similar, please let me know! Thanks much!

sc250tt

So the ecu did not help....What is the milage on your car? how does the engine harnes look?

94SC4

Mileage is 160K miles .... the engine harness is good (at least it looks good). I keep the engine bay and entire car very clean and it's bone stock. I might stop off at another dealership and talk with them about diagnostic equipment. If there would be a computer they could hook up at the ECU and record the engine functions, then it would seem a lot easier to diagnos as it's got to either be air, fuel, or timing. I might also just replace the coils, plug wires, plugs, rotors, and caps to see what happens. That's about $500 but I don't think it will help.

sc250tt

You havent replace the coils or wires or cap and rotors yet? That should of been the first thing to rule out.

dwebb99

iTrader: (17)

BTW, Autozone will run a diagnostic check free of charge with their code reader. I believe O'Reillys will and perhaps Advance Auto Parts. I KNOW for a FACT (here in Houston) Autozone will do it for free. Nice engine bay you have!! Good luck. If it is not spitting out any codes, then it is going to be PITA to begin your troubleshooting procedures. Let us know what you find

SHOLEXMAN

Well here is my 2 cents. It doesn't sound like anything electrical or sensor issue. You need to have someone hook up a fuel pressure gauge to your fuel system and run it and see if you loose pressure. If the pressure goes to around 10psi or less you have your restriction. IF you have a pre 95 you can try to hook it up to the cold start injector with some temporary modification. Or try and hook it to the main feed on the passengers side fuel rail. If your filter was replaced 50k ago your due for another one. You need to look at your fuel lines for anything pinched or would cause a restriction. Since your fuel lines run near the pinch weld they might have pinched it when your car was last serviced. As for (dwebb99) you talk a smack about dealers. One thing not all are the same especially if there independently owned and not by a corporation. The prices are high what do you expect it is a Toyota with chrome! It is targeted for rich older people in there 60's not 29 to 16 Jesus. You haven't been to all the dealers so don't through them all in the same band wagon. Thats how threads get closed cause you start ticking people off.

dwebb99

iTrader: (17)

Not intentionally trying to tick anyone off. Perhaps a new thread should be started. Who likes their Lexus dealer service department, the quality of work, and their pricing, AFTER their car warranty expires? If you love'em, who are these Lexus dealers and where are they located? Inquiring minds want to know....

94SC4

Thanks for all this information. Sometimes it's easy for me to get a little tunnel vision and the comments and ideas are very helpful.

I did replace my engine/tranny mounts so maybe jacking up the engine caused a fuel line to get pinched. I'll examine the lines but also I think I'll go to the dealership and see if they'll do the pressure check.

I also think I'll replace the wires/coils/etc just to be sure that's not the problem. Does anyone know if the ignitors can be an issue - they're a bit pricey at $350 each.

SHOLEXMAN

If your ignitors where bad or just 1 it won't run right or at all. You would have a check engine light with a electrical circuit malfunction. Not the issue sorry. To (dwebb99) there doesn't need to be a new thread that is over the top and not worth the time. There are already enough biatching threads on pricing of parts/service. My dealer for one thing does quality work and we have the top Lexus techs in the southern district. Our dealer bends over backwards to make the customer happy. We have surveys that go to every customer and we know if it is a bad experience. I am not going to list any other dealers cause I don't work there and the list could go on. Not worth my time.

v8soarer91

take the engine ecu out of the car and take the lid off the ecu so that you can see inside and check if there is anything out of the norm like.

enlarged/swollen or burnt capacitors (bad)
blown resistors
blown diodes etc

replace or get a new/used ecu

then id recommend replacing

leads
platinum sparks
cap and rotors

then fuel system

pump
filter

and check the lines on the fuel pressure regulator

then start replacing the sensors

dwebb99

iTrader: (17)

ahhh....did the driveability issues begin RIGHT after the engine mount install? If so, perhaps a mechanical or electrical connection got tweaked...?

dwebb99

iTrader: (17)

BTW 94SC4, on my old Mr2 Mk1 several years back, I had a similar driveability issue with my Mr2. On acceleration thur the gears, the engine would have sporadic/random cutting out. Troubleshooted the fuel system, all was fine there. Went to electrical troubleshooting(testing the coil and ignitor) and quickly sourced it to a bad ingnitor (which attaches to the side of my coil). Replaced it with a junk yard one and ran like a top once again.