Limp mode P1241 with big bore throttle body.

LVSBB6 · Oct 5, 2009, 02:36 PM

So I have installed the JUN big bore throttle body in the car yesterday, definitely felt some noticeable gains from this part and was running fine initially.

However I have been driving around for a bit today and triggered CEL P1241 - (Torque monitor) many times on the road, the car also went into limp mode and cut powers out completely.

I tried increasing the Air Flow Limit Table a bit at a time throughout the entire load/rpm range via Cobb ATR, but still haven`t completely solved the problem yet.
Everytime the problem occurs it would go into limp mode, all have P1241, one time even accompanied with U0167.

The CEL pops up mostly during cruising in low throttle/load around 2K-3K rpm, but it occurs even by tapping the throttle under some circumstances. High load or WOT would not trigger the CEL.

What can you suggest here? Should I keep increasing the AFLT in the low load/rpm until it solves the problem?

JUN stated that this TB increases 20% of air flow and 15% of intake volume over stock and, how does this affect the figures in the AFLT? Logically I should increase the values throughout the entire range, but as I said only the low load/rpm seems to be the problem so far.

I`m sure many of you are looking into the big bore throttle body down the road, looks like it`s not as simple as plug and play. Getting this problem solved will surely help out alot of time/trouble for the community.

Experts please chime in! Thanks.

ScottSpeed21 · Oct 5, 2009, 03:43 PM

Did you modify the values in the Torque Limit tables also? The 1241 Torque Monitor code comes mostly from Torque tables and not so much from the Airflow tables. If you can repeat the 1241 pretty easily, run a log while you trigger it to see what kind of load you're at, then raise the values around that rpm/throttle postion area accordingly.

LVSBB6 · Oct 5, 2009, 04:01 PM

No I haven`t modify the Torque Limit table as I heard it associates with P1238.
While P1241 is comes mostly from the Air Flow Limit Table. Can somebody confirm this is true also?

I`m hitting the CEL at very low throttle/load input, sometimes even just by tapping the throttle when rolling to a stop.

Quote:

Originally Posted by ScottSpeed21

Did you modify the values in the Torque Limit tables also? The 1241 Torque Monitor code comes mostly from Torque tables and not so much from the Airflow tables. If you can repeat the 1241 pretty easily, run a log while you trigger it to see what kind of load you're at, then raise the values around that rpm/throttle postion area accordingly.

ScottSpeed21 · Oct 5, 2009, 04:08 PM

I've found that the 1241 and 1238 come mostly from the Torque tables while the 1235 is mostly from the Airflow tables.

If you're throwing a limp mode from very light throttle, your values are probably too high at low throttle/rpm points. This means according to the tables, instead of reaching load too high, you're not reaching load high enough for that given throttle/rpm. You'll have to lower some values down low on the table, and you can still log where the load is when you hit the limp mode.

Too bad we can't write the 12xx disable codes into our AccessPorts...

seven_227 · Oct 5, 2009, 04:11 PM

Hope u get it solved soon.

LVSBB6 · Oct 5, 2009, 04:23 PM

Thanks for the explanation, I didn`t know there would be problem if the limit is set too high. And I wouldn`t expect going to a bigger throttle body would actually make lower load at certain rpm.

Should I adjust the Torque tables only in this case, or both the Torque and Airflow tables?

Quote:

Originally Posted by ScottSpeed21

I've found that the 1241 and 1238 come mostly from the Torque tables while the 1235 is mostly from the Airflow tables.

If you're throwing a limp mode from very light throttle, your values are probably too high at low throttle/rpm points. This means according to the tables, instead of reaching load too high, you're not reaching load high enough for that given throttle/rpm. You'll have to lower some values down low on the table, and you can still log where the load is when you hit the limp mode.

Too bad we can't write the 12xx disable codes into our AccessPorts...

ScottSpeed21 · Oct 5, 2009, 04:40 PM

Your best bet would be to go back to what the tables were set at before you raised them again. Highlight an area from 2000-4500rpm and 20-40% TPS on 1-3 Airflow and 1-3 Torque Limit tables. Lower that area about 10-15 points, save it, flash it and go take a drive. If you throw the code again, pay attention to what rpm you're at.

Hiboost · Oct 5, 2009, 06:56 PM

Sounds like the torque and/or the airflow tables are too high at light throttle lower RPM. Likely you were right at the edge of triggering the "not enough airflow" codes before and the larger throttle body is possibly losing a slight amount of registered load until boost builds enough to take advantage of the extra flow capacity. Until you reach full boost it's likely slightly hurting airflow at low rpm's.

LVSBB6 · Oct 5, 2009, 08:23 PM

You guys are probably right on, I tried what Scottspeed suggested and the CEL hasn't come on yet. Will keep you guys posted if it happens again.

On the positive note, the gains of the JUN TB is very satisfying. The additional power can be felt all the time while driving.

ScottSpeed21 · Oct 6, 2009, 12:18 AM

Sounds good, keep us posted.

What Hiboost said about the "not enough airflow" code makes complete sense since generally a larger throttle body will sacrifice a little on the low end for more top end flow.

LVSBB6 · Oct 6, 2009, 09:55 AM

The limp mode happened on me 3 times this morning during traffic hours when i tried to make my way through the traffic. It happened around 2300rpm, 2500rpm and 3700rpm just after i switch from 1st to 2nd or 2nd to 3rd gear with very very light throttle input, even just tapping it i would say.

Which load cell should I be focusing on in this case?

LVSBB6 · Oct 6, 2009, 01:02 PM

So I did more testing this morning and can now narrow down the problem area between 2K-3K rpm with very low load. If I drive constantly within that rpm range doing upshifting, the CEL will hit on me with limp mode.

I have focused my adjustment between 2K-3K rpm, 10% to 35% load. Started by lowering the values, until I hit what I believe is the threshold and the CEL code changed from P1241 to P1235.

Now if I don't get either the P1241 or P1245, it would give me P1234 and P0223 at the same time.

I'm still testing as we're speaking, let me know if you have more suggestions. Thanks!

ScottSpeed21 · Oct 6, 2009, 03:17 PM

Quote:

Originally Posted by LVSBB6

So I did more testing this morning and can now narrow down the problem area between 2K-3K rpm with very low load. If I drive constantly within that rpm range doing upshifting, the CEL will hit on me with limp mode.

I have focused my adjustment between 2K-3K rpm, 10% to 35% load. Started by lowering the values, until I hit what I believe is the threshold and the CEL code changed from P1241 to P1235.

Now if I don't get either the P1241 or P1245, it would give me P1234 and P0223 at the same time.

I'm still testing as we're speaking, let me know if you have more suggestions. Thanks!

The same thing happened to me. After I tuned out the 1241 and 1235, I would hit 1233/1234 all the time at very light throttle. Keep lowering the values on the low end 'til the codes stop, and make sure you're making the changes to 1-3 Airflow and 1-3 Torque tables.

LVSBB6 · Oct 6, 2009, 07:58 PM

Did you mean I should keeping lowering the value even if I see P1235?

I was under the impression that P1235 meant the values was too low, while P1241 means the values are too high. As it seems like the trend it as I was lowering the values. Please confirm.

Quote:

Originally Posted by ScottSpeed21

The same thing happened to me. After I tuned out the 1241 and 1235, I would hit 1233/1234 all the time at very light throttle. Keep lowering the values on the low end 'til the codes stop, and make sure you're making the changes to 1-3 Airflow and 1-3 Torque tables.

ScottSpeed21 · Oct 6, 2009, 10:13 PM

Yes, keep lowering the values until you're not throwing codes at light throttle. Any of the 12xx Airflow/Torque Limit codes can trigger with either too much flow or not enough flow. Unfortunately, they don't specify if it is too much or too little flow, so you have to determine that by when and how the code is triggered. If you're still triggering 12xx codes at light load/throttle, you have to lower the values some more on the low end of the tables, regardless of which specific code it actually us.

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