Having water meth injection does a great job of reducing intake temps. It also makes your AFRs richer, so usually the tune compensates for that by leaning out the fuel map.

Not too long ago, I was doing a 15psi (EFR 9174) log run. WOT 3rd gear pull and around 7,200rpms the power cuts off for a second, so I release the throttle and resume normal driving back to the house. On the way, I did a couple smaller pulls and everything seemed just fine. While reviewing the log file, I could see that right at 7k rpms my intake temps started climbing really fast from 83F to 153F, within 400rpms. Also, during the same time AFRs went from 10.3 to 12.3 causing the engine safety to kick in, which is why I felt that power cut.

The only thing that makes sense is that my water meth for some reason stopped spraying. The tank was half full and it has always worked without issues before and was working fine again after the incident.

My question is, anyone think something else happened? Other question is about the tune. The safe thing to do is tune the car with good AFRs without the water/meth, then add in the water meth for advantages. However, since it lowers your AFRs, does it affect the way the engine runs the same way as adding too much fuel, resulting in misfires?

 

what is your base fuel?

how much water meth? what system?

what ECU?

any knock reading?

what IAT sensor?

 

Running dual walbro 450 pumps with the Turbosmart 2000 FPR set at 43.5psi base pressure. - Logs show fuel pressure was consistent the whole time

AEM V2 Water/Methanol Nozzle & Controller Kit which was installed by Sakebomb garage when the previous owner had them work on the car. I'm running the standard boost juice 50/50 mix.

Adaptronic Modular S6. However, I'm ditching it for a Haltech Elite as soon as it's not 115F outside and I can work on my car.

No knock sensors installed. Will install with Haltech Elite

IAT is factory location mounted fast reacting IAT sensor.

Fuel pressure looks fine the whole time, only thing that stands out is the IAT shooting up and AFR leaning out at the same time.

See attached part of the log where this occurred.

 

AEM shows nozzles of 250, 500 and 1000 CC/Min. do you know which you have?

 

I do not... I have been wondering the same. Sakebomb tuned it with that AI system while they had it, so I assume they would have used the one they thought was the best.

What does Howard use for a 500rwhp setup such as mine? Street ported engine with an EFR 9174 and and all the supporting mods.

 

I would imagine they would have stuck the 1000cc injector at that kind of power level. One possibility is that it could have reduced flow through the injector or it got clogged or something along those lines. The one thing I don't like about the AEM kit is that it doesn't have a flow sensor and you have to buy it seperately and incorporate it in your system. Might as well pull out the injector and run the test function on the controller to check spray pattern.

 

Right, I agree. It was working properly again that logging run. I did a couple pulls afterwards, in 2nd gear (I had not looked at the log yet to see the issue that occurred), and log shows everything was proper for the pulls afterwards. Test function works just fine as well.

The plan was to keep going to 20psi on the tune, but I don't feel comfortable relying on the AI system for safety after that issue occurred. The only AI system change that I did after buying the car was completing the Sakebomb kit with the euro style tank. This car actually came with the AEM pump mounted under the car already, the same bracket they currently sell, but I have the prototype. While the car is down, the plan was to shorten the line between the tank and the pump and make it more direct, instead of looping around and going down the fuel pump cover.

 

a 9174 at 15 psi around 7200 rpm could be making close to 500 rotary rwhp. (65 pounds per minute is 489)

500 takes 3946 CC of gasoline.

according to your log prior to the event you show 12 data points and the average AFR is 10.42

at the event and forward there are 6 data points and the average AFR is 12.31

you lost 18.41% of your fuel and your fuel pressure was constant.

your AI system is not the culprit here.

IF you have a 1000 nozzle you were delivering 500 CC of methanol

to factor the effect we need to correct the meth on a BTU basis to gasoline

500 X .493 = 247 CC of gas equivalent.

247/3946 = 6.2%

if you lost your AI your average AFR (10.42) would have risen to 11.07 and caused no problems.

your AFR rose 18.14%

i would be looking at your fuel injectors or fuel injector controls. if you are running a Ground Zero LIM and have 6 injectors the math becomes supportive as

6 X 18% is 108%... pretty close to 100% and pointing toward one injector.

i do see weirdness re your temp data... your temps stair steps like the typical thermistor trying to catch up with reality from data line 2 to 8 arriving at 116 F. then the linear stair stepping stops for a couple of lines and the next line is 182 F!
after the immediate arrival at 182 the thermistor starts stair stepping attempting to, again, play catch up. i switched to air thermocouples in 2012 as they generate 4 samples per second and are dead accurate so i am not familiar with "fast" thermistor sensors. i did recently install one along with my air thermocouple and will shortly have comparative data.

it appears to me that your sensor is playing catch up early and then all of a sudden in less than a tenth of a second goes from 116 to 182. i hope to get some data that might have a bearing re your situation.

the other interesting item in the log is your RPM drops 473 in less than a tenth of a second while your TPS is still max.

to be continued...

 

Thanks, Howard. Exact reason I posted this up. My remote tuner's excuse of my AI system failing me did not add up to me. I'm starting to think its the Adaptronic ECU. I've had to send it in to get both MAP sensors repaired and it cutting out during logging sessions. Even had a corrupt logging file. However, I have no proof, just a suspicion. Thanks for doing the math.

I do have the Xcessive LIM with a total of 6 injectors. They are all ID brand. Two primary are used and were cleaned recently and the secondary four are brand new. 1k cc primaries and 4x 2k cc secondary.

Check out this attachment. I just noticed that rpms did drop 473 within a tenth of a second, then came up again the next tenth.

 

i don't have a lot of ecu tuning experience, but i see that your fuel pressure was constant 43psi across the entire throttle, im 90% sure the fuel pressure normaly rises up to around 65% (ideal/safe) safely while creating more boost and leaning from the rich AFRs. Someone can correct me if I'm wrong but i got that info from this forum as well as other fd3s tech sites. And just my knowledge and experience with fuel pressure regulators.