With larger injectors and no electronic engine management, do you get a P0101 CEL (MAF out of range)? Does the Treadstone velocity stack solve this? Does it throw any codes? Has anyone found a way to eliminate the P0101 CEL without clamping the MAF with a piggyback?

I would really appreciate any suggestions but please don't bother to post any one sentence "you need EM and tune" replies without explaining in detail why it's the only possible way to eliminate this CEL code. TIA.

'08 XB2 with CXR kit. 50 trim T3/T4 (60/63 A/R), 440cc Deatschwerks injectors, SMIC, Type S BPV, 2.5" intake pipe and DP. Running 5psi max. Closed loop afr 14.7:1(+/- 0.5:1), open loop afr ranges from 10:1 under vacuum load and 11.5:1 under boost. Idles perfect and drives like stock until boost hits, running on the stock ECU.

I think the problem is simply that the MAF readings don't match the fuel trims required because of the larger injectors. I installed the injectors a week before the turbo to see how the ecu would respond and got the code then too. If the velocity stack works, I could probably rig something to make the MAF see more air or possibly modify the MAF signal.

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uhhhhh not to be a jerk but tune for it or geta code reader and clear that ish. see how quick it comes back.

 

The MAF sensor is a Karman style it reads off pressure waves coming back to it from a column of air. A velocity stack might skew the readings at a certain point in the power band under ideal conditions but I do not think that it will cover all conditions or variables. It obviously is not the ideal setup, ann I'm sure you know this.

You may be running 14.7 at idle but I would think that the long term fuel trims are doing all they can to scale back the fuel delivery at that point. Once you reach the outer limits of the ECUs ability to scale fuel it will start setting codes.

In all honesty if a mechanical fix was the best solution then the OEM manufacturers would have stuck with using carburetors. It is not the best solution for your situation and I think you know this. It would be a lot cheaper to tune this thing the right way the first time then to fix the resulting engine damage from cheaping out.

 

I have a ELM327 OBD2-USB2 adapter, a netbook and various OBD software. I've reset the 101 code numerous times and it comes back pretty quickly. The only other code I've seen was a pending P0172 (rich) code. I reset that and it hasn't come back. No codes relating to misfires which could indicate detonation or really bad afr.


I'm 99% certain that I have a Denso platinum hot wire MAFS. It seems to me that most engine sensors can be used to slightly modify or "tune" ecu behaviour. Add or subtract a little air or signal from the MAF, alter the CTS or IAT resistance and you can fool the ecu into making small corrections. Similar to how a piggyback does by intercepting the MAF signal and feeding back an altered and clamped signal to the ecu. Of course I do realize that any such mods require a bit of trial and error to get right, are limited in scope and that altering one sensor to say lean the afr a little may also have unwanted side effects such as advancing the ign timing a little.

I'm just curious to see how much I can do with the stock ecu. After all, the oem learning ecu is a lot "smarter" than any piggyback FIC. It's not about cheaping out, more like holding out until someone offers a PnP FIC harness for my car.

BTW, I have a water/meth injection kit going on very soon to address detonation concerns. Just in case 93 octane, 11.5:1 AFR and the knock sensor can't handle 5psi. I'm also still considering the TRD SC reflash because it would most likely eliminate the 101 CEL but I'm worried that it might mess up my already good AFRs and pull too much timing.

Thanks for the EM and tune advice. It's probably my best option, but I'm not yet convinced that it's my only option. FWIW, Todd from TT said that there is a TC in AZ that's been running great for 2 years on 5psi and the stock ecu.

 

that p0101 code seems odd because your not doing anything to the maf......it doesnt seem right to me at all....now the rich code is absolutly normal for no managment and larger injectors...even with managment you can still throw that code for having your fuel trims out of wack...

something i suspect has happend to the maf..either its dirty or damaged or its not seated right. you also could have a charge pipe that is loose and can throw that code but normally youd notice the drivability is sucking a bit...then again it could be a small leak....so in short, check your maf and check your pipes....good luck and try to find some managment if you want to go up in the power. aem fic is a good starter managment if set up properly.

 

All I can tell you is that I had a CAI installed for over a year, a header for several months and never threw a code. I installed the new injectors without touching anything else and got the P0101 code the same day. I reset it and it comes back within a day every time.

The only explanation I can come up with is that the MAF signal is (as the P0101 suggests) 'out of range' for the fuel trims required with the larger injectors. The ECU probably expects less air because of how much fuel it has trim to hit it's target 14.7:1 AFR. I've cleaned the MAF and checked and double-checked for any leaks and couldn't find any.

As an experiment, I taped off a small portion of the MAF air intake tract to reduce the air seen at the hot wire and took a test drive. I didn't get the CEL but it showed up as 'pending' so no joy there. Besides which, when entering open loop the AFR went too lean before correcting itself to the usual ~11:1. I took the tape off and have given up on modifying the MAF to eliminate the CEL. My last hope is a parallel potentiometer on the IAT to raise the IAT readings. Since my actual post-turbo IAT is much higher than what the IAT is seeing near the air filter, I'd just be 'correcting' it and the ecu would calculate less air based on the lower density of hot air. Maybe...

Thanks.

 

what size intake pipe are you using? 3"?

 

2.75", same as the CAI and the oem airbox.

 

idk what to tell ya...i highly doubt its due to the injectors.

 

I forgot to mention that I did change something else when I installed the injectors. I added my UEGO and boost gauges. I tee'd the boost gauge SU off the post-TB vacuum line and cable-tied the connections. It doesn't leak. Simple cause and effect indicates injectors but this wouldn't be the first time coincidence threw cause and effect out the window.

I found a good Toyota PDF on testing procedures for this code and I'll try that. It sure would be one helluva conincidence if the MAF went bad the same day I installed the injectors but it's possible. Thanks for your help. If I find the cause or a fix, I'll post it up.

 

k
K

 

you will get this code till your tuned trust me its the way it wokrs

 

It seems that way. I bet if I put the oem injectors back in, the code will go away, but then I'd only be able to run maybe 4psi. Not worth even trying it. I'll just live with it for now. At least the VSC is off all the time.

BTW, how much vacuum does your engine pull? Mine pulls ~26psi at idle and as much as 30psi.

 

so your going into boost without managment....i know that sounds like a stupid question but i had assumed this was going on even after the code had been cleared and staying out of boost...so yeah your deff going to get this code...the ecu is seeing the boost and is freaking out, well the maf sensor is going nuts...lol

 

Actually, the code appeared the day I installed the new injectors, 2 weeks before the turbo was even installed. I reset it numerous times in that 2 week period and it would reappear as 'pending' even while idling in my driveway. Installing the turbo and running boost hasn't seemed to have any effect on it. I reset it tonight while just idling and several minutes later it appeared as 'pending'. The actual CEL won't set until the second consecutive warm-up cycle where the MAF voltage is considered "out of range" by the ecu.