Hesitation/Miss at constant throttle...

[thedave925]

affirmative on the 24, odd that with the lexus afm and running afc mode that you would see code 24.
24 can retard timing making driving less enjoyable.

34 is hitting boost cut or at least moving more air than the ecu thinks you should be, not really afm related unless you downsized from the lexus afm and forgot to modify 'main' under the settings menu on the maft.

Bummer that the coil packs are going, congrats on getting closer to getting a solution.

 

[CajunKenny]

Thanks for confirming 24!

I'm still on the stock afm. Could that be the main culprit...the restriction?

 

[CajunKenny]

I switched out the afm and the code 34 is gone. At least for my short run up and down my street...

Code 24 is still there and if it's messing with timing, that could be the cause of what I'm feeling while driving.

Is there a way around this besides installing a lexus afm and/or converting to speed density?

Maybe back the screw all the way out of the afm...??

 

[thedave925]

If your using the maft-pro to scale the airflow to the ecu, where your settings are set for a lexus afm, and you change to the oem afm without reskewing the airflow with the settings, then suddenly at speed the oem afm is reporting less airflow than what the ecu is expecting for that load and engine speed.

But that shouldn't give you a 24.
24 and 31 is what you get when the afm is unplugged. Happens to many maft installs apparently.
24 is the air temperature signal missing. Its said that installing a resistor inline will make up for the maft not being fully online at start up, making 24 go away.

I had a 34 on a stock system from a bad oem bypass valve (toyota's BOV) and holey intercooler and piping.
You'll reach boost cut faster using the oem afm.
the lexus afm gives you another 25% margin of flow before boost cut, coupled with 550s will prevent lean engine conditions. Don't ignore the fact that running the lexus afm with 550s in afc mode on the maft pro means you don't have to scale your 'main' setting -25 to make up for the larger injectors. Would the ecu detect that your running rich from having 550s by using the o2 sensor and 'deduce' your moving too much air and give you 34 that way?
Maybe you have a boost leak? Maybe its a code from the past as well LOL
Gosh sometimes i think cars are like 1000pc puzzles, not impossible but a lot of trying out options...

 

[CajunKenny]

I've never run the lexus afm. Only the stock afm.

My maft settings are setup according to the setup guide. I'm still running v4.4.

I'll attach my .adl if you feel up to reviewing it. Note the oscillation of the afr data stream while at constant speed. Does that look similar to yours?

Thanks for your input thus far Dave!

 

[CajunKenny]

Ok. Dave, this is for you!

My 24 code, and so far my 34 code also, was corrected by disconnecting the brown wire of the maft. I had it connected to the 'THA' line.

I give all the credit to TurboBob on Fullthrottletech.com.

Here's the link:
http://fullthrottletech.com/showthread.php?t=5071

Now that that problem is currently solved, I can now focus back to my original problem. The hesitation/miss...

I have changed the following thus far:
AFM
Plug Wires
Coil Pack

Still have the problem so I'm going pull my plugs and gap them to .028. While the plugs are out, I'll do a compression and leak down test.

 

[thedave925]

I have a lot to say, take with a grain of salt as it tracks many places. The bold is the point of the post

My misunderstanding, i had the impression your using the lexus afm with your 550s.

What brand and plug type are you working with?
I recently went from autolite 3933?s to try ngk 2330 (BCPR6ES) plugs and the idle popping i have got more frequent.
I think its time for me to change my wires, and do different plugs, say, ngk4644s this time around.

Turbobob is the man and its awesome to have had his full attention on the maft-pro as long as he did.

I didn't know your still running version 4.4. Update to at least 4.65, you'll see that the engine hesitation on tipping in the throttle will be just about gone.

jeeves on fullthrottletech noted that your MAP is -14.xx, which shouldn't affect the maft outputs as long as the maft is set to get its readings from other sources.

Back to engine occilation, I still get the impression that the ECU is getting 2 signals causing your situation. As if your afm is going straight to the ecu, but then you tee'd in the green wire from the maft too, which is causing the ecu confusion.

What is your Aux1 readings like?

Looking at the fullthrottletech screenshot jeeves put up shows me that other than the occilation MAP shows, the ecu has good control in closed loop to maintain stoich fuel mixture until it goes to open loop mode where full rich is what happens. It might not be so rich now that code 24 is not an issue.

I thought that to use afc mode the maft's yellow wire intercepts the KS wire (light green) from the afm, then the maft 'alters' the signal, and then the maft sends the signal on its way using the green wire connecting back into KS wire to the ecu.
As in the maft is a bridge in the break of the KS wire, if you get my drift.

OR

maybe, assuming the maft is correctly wired, the maft is set to receive its input from 2 different sources that don't correlate. Which means you should check its settings to make sure that its not reading/integrating/sending MAP signals when you aren't using it.

I pulled my maft manual and got myself all confused again LOL, more studying to do

 

[CajunKenny]

I just re-read my post Dave and I didn't meant it to sound like it did. When I said that "Dave, this is for you!", I was excited because disconnecting the brown wire cleared 24 for me and was thinking that it might do the same for you!

Those are the plugs I'm running. The NGK 2330's. They have about 6k on them. Plug wires are a good used set. One of my spare sets...

Yes, I have the maft pro connected in a manner that it intercepts the AFM signal, does it's thing, and continues it on to the ECU. Not T'd in.

It is installed like this: AFM--->Maft--->ECU

When I installed my maft I apparently used outdated instructions. Bob and Jeeves got me straightened out on a few things. I should however go through all my settings... Here's where v4.65 or higher will come in to play. I will get it updated.

I grabbed a couple of screen shots and posted them on to the attached word doc. The screen shots are of the exact same point in the log and are at a point in my drive where I was at constant throttle. The oscillation is quite noticeable on the second page.

The first page will answer your question about 'Aux1' (which was at 0) and so on...

 

[thedave925]

i can see the screenshots in jpeg and bmp but i don't have word so i can't see it, sorry Kenny

Other than idle popping, those plugs wouldn't cause ocillation.

So the next piece of the puzzle is to figure out what will make the ecu happy, it should have a Aux1 reading, and 0 means something is not matching what the ecu thinks is ideal.

The ecu can fight PTT, causing ocillation when the ecu is reading 0 at the Aux1

The only idea i have right now is to rejoin the the KS wire to exclude output of the maft and see what happens.

If it continues ocillation than perhaps its a different output of the maft causing the issue or maybe entirely not maft related.

If it ceases ocillating with the KS in a continuous run, the issue is soley maft related, which means your settings need a review.

When i first installed my maft, I had the same maddening ocillation issue but not as extreme. That was when i first attempting to utilize afc mode for base tuning. PTT made the car drivable, but it was not a joy.
I ran out of ideas/patience and went full SD mode. Throttle response was crisp and mileage went up.
BTW I'm running version 4.80. I haven't gotten around to any updates for a long time now lol

 

[CajunKenny]

Ok. I figured out part of the problem. I feel a little stupid that I didn't check this earlier; but, I started pulling spark plugs to inspect them to decide whether or not to replace them.

When I pulled #6, it was badly covered with oil. So much so that I was losing spark. Car pulls much better now!

I'll have to do a log with the maft now to see if my afr's are still oscillating as badly.

This find does lead me to my next question... Does anyone know the part number of the gasket used to seal those big bolts in the oil galley?

I once read a thread where someone posted napa part numbers for that; but, it was a loooong time ago and I doubt I could find it again.

 

[CajunKenny]

Does anyone know the part number of the gasket used to seal those big bolts in the oil galley?

Anyone?

 

[CajunKenny]

Bump...

 

[rayall01]

Ok. Does anyone know the part number of the gasket used to seal those big bolts in the oil galley?

I once read a thread where someone posted napa part numbers for that; but, it was a loooong time ago and I doubt I could find it again.

I just used lots of teflon tape, Working well for me so far.

 

[CajunKenny]

Hmm...I never even considered teflon tape because of the heat. I've also got some thread sealer; but, don't trust it implicity. I'd like to use a gasket with it just to be on the safe side.

But, yeah...thanks for that suggestion!

 

[thedave925]

Are you talking about the "#3 cylinder head cover" gasket, as shown in the tsrm?
And the large diameter allen bolts that hold it down, I think there's 3, down the center of the head from front to back?
EPC number 11219-42020

http://www.cygnusx1.net/Supra/techtips.aspx
^^Has the Electronic Parts Catalogue and Toyota Supra Repair Manual
and various tips

 

[CyFi6]

Did you ever solve your misfire Kenny? I am experiencing something similar and would be nice to get a starting point. I have already ruled out mechanical as the compression test passed. Low load= pretty bad misfire. Any kind of throttle or load and there's no misfire, but idle or 2500rpm in neutral and its pretty bad.

Got iridium NGK plugs
NGK wires- less than 15k miles
coil pass resistance checks
Rewired my CPS