Make Sure The Part # On The MAF is The Same Just Because It Plugs In Doesn't Mean It's Looking For The Same Things

 

Checked. And check. Each MAF I have tried (four, at this point) has been a correct match.

I'm going to change out my O2 sensors this weekend, weather permitting. If that doesn't do anything, I'll try fiddling with the TPS. The only reason I think the TPS may be involved is because the issue is largely dependent on the actual throttle position.

 

To update the thread. Today I went out to a local guy's place to pick up a TPS and IACV. I got there and we swapped in the new TPS and calibrated it with a multi-meter and feeler gauges. In spec, problem was still there. He called his buddy who is a 20+ year tech at the local Lexus dealer. Advised to check coils. I was reluctant because both of my coils are less than 8 months old.

Anyway, we swapped in a new (used coil) and voila! Hesitation gone. Drove the car about another 70 or so miles today and no issues thus far.

Turns out my valve covers leaked oil on to the driver's coil and caused it to fail. So I stopped by the parts store and bought new valve cover and throttle body gaskets. I'll tackle those next weekend and do a thorough engine detail. Noticed a lot of sand, dirt, grime, and debris around the engine that's never been there before. Chalk it up to modified wheel well liners and under-engine cover.

So, big thanks to Darryl G. for supplying the part and taking the time to test out alternatives. He definitely went above and beyond the call of duty for a parts recycler. If anyone around the country is looking to have their ECU rebuilt, he does it for (I believe) $159 or so and offers a lifetime warranty. He also stocks all kinds of SC parts and from what I've purchased from him, offers prices better than even most FS listings here on CL. Feel free to PM me if anyone is interested in his contact info.

 

Excellent post!
I have a 2003 GS430 with exactly the same issue. No one seems to be able to help and I had done the MAF as well. I will try the coils next.

Crossing my fingers.

Thx for the post and closure.

 

Hadn't seen this thread before bstarr's bump. Why would changing coils affect something symptomatic to the MAF? I can't figure out what the connection would have been there.

 

Me either, but for $80, I'll buy one and see. My car is a lot newer than his, but the principals are the same. I'm doing mine this weekend, so I'll post my results.

 

Well, my reason for asking is it seems like a coincidental fix. A failed coil wouldn't magically start working again with the MAF disconnected... Mongoose's problem sounds very much like TPS, and since TPS and coils were done in the same session, I'm wondering if the TPS really is what fixed it but it didn't become evident until the ECU was reset or something. (Any time the MAF is messed with, it's supposedly important to reset the ECU.) Swapping coils would have meant disconnecting the battery and resetting the ECU in the process ... just thinking out loud here.

But if you want to throw away $80 on the off chance a logically unlikely fix solves your problem, I'd be glad to PM you my PayPal address.

 

The principles are not the same on a GS430 as it uses individual coil on plug, so you have 8 smaller coils to replace instead of the normal 2, and majority of the time you would throw at least a misfire code for a bad coils on obd2 with individual coil on plug.

SC400 is an older system as it uses 2 ignitors, 2 coils and 2 distributors and plug wires to each coil.
The gs430 does not even have a distributor or plug wires, and the igntor is built into each coil.

 

OK...I see the light.
I was really hoping that his fix was my fix since our complaints were exactly the same. I don't know the SC400 so I was assuming it had the same set-up.

So now that we're here... Any idea's on the 430?

 

hesitation or running rough could be lots of things, I believe the 4.3L has vvti so it could be related to the oil control valve even. just throwing things out there you probably want to start a thread in the 430 section with all the details cant just list everything that can go wrong you know. chances are your symptoms aren't exactly the same every bit of info is usually helpful.