The heat is messing with my RB!

[DriftingisLame]

Okay, Recently I moved to Phoenix, AZ where I believe my car has developed a few problems due to higher heat than Oregon.

I installed an aftermarket water temp gauge since I figured I'd have an issue or 2 with cooling. Recently when the engine reaches operating temp the car wants to die sometimes at idle. just die, stabbing the throttle does nothing... Needle dives, and theres no stopping it. If I try starting it immediatly after it dies, the starter just spins and spins... Wait a few seconds and it will start right back up.

Yesterday I came across a Lamborghini Gallardo and raced him, I noticed when I got off the freeway my water temp was pretty steep, 220-225, then the engine died just like I explained its been doing. So I start it back up after a few seconds and drive it to the nearest drive way and cut the engine to let it cool. Ever since then when my car is at normal operating temp, I CANT let it drop below 1700-2000 rpm or else it will die! This means a lot of revving at a stop, a lot of slipping of the clutch, or launching out of stop signs... No joke, if I let it drop below 1700-2000 it will die regardless if Im moving, on the throttle, or just sitting there, it will die! Or, it will idle in a very strange way.. Its like the worst miss I've ever seen, like 2 cylinders, like it only fires every other rotation of the engine. Not enough power to get the car moving. If I can even get the motor to rev at this point and I successfully get the RPM's above 2000 or so, it runs normally, no missing at all, no studdering, the car is normal.

I'm throwing codes 12 and 34, which I believe are MAF and Knock sensor? What does the knock sensor have to do with this, I cleaned the **** out of my maf and its still not working... Could the maf be the problem? I wasnt throwing a code before this problem started.

Car runs perfect when I start it up cold, and drive it for 10-15 minutes.

Any help is greatly appreciated, this car's my daily driver in a new town and its necessary for survival.

Thanks!-Max

PS: Here's the race between me and the gallardo if anyone cares.

http://www.youtube.com/watch?v=b-YRqe28VdQ

The guy had more money than driving skill obviously, I saw/heard him downshift, and heard his motor untill I was too far away... I know he was on it because I let off at about 125-130 and he was going pretty damn fast himself. Reason I think I won is because he is a tard and wasnt in a low enough gear.. Whereas I was in the ideal gear, brake boosting, and ready to rock. Oh well, it was awesome seeing such a sweet car anyway!

[rotorimp]

Is the stock temp. sensor still wired to the ECU? You will throw a Knock code because of the misfire. Is your consult plug wired up? You could be having these problems because the ECU is not getting the right motor temp.

[Carl H]

check wiring to the maf, and maf to see if it is suspect.it sounds like the ignitor is going out on your car, especialy with the extreme heat your motor is seeing at those tempatures.i would reccomend replacing it, if it starts effin up it can ignite the mixture at the wrong time thus causing it to knock then throw the knock code.reset the ecu to clear the knock code.

[rotorimp]

I have had MAFs go out and usually the don't run above a certain rmp--Still worth a check.

[DriftingisLame]

I have a late model rb20 so I used a SOHC ka water temp sensor, and spliced on that plug, its always been the way it is and I dont really get why that would cause the problem now. Just like my MAF wiring, always been the same, never had a problem...

Good advice guys, I'll get my spare ignitor shipped here from back home and give that a shot..

[DriftingisLame]

Let the car idle until it was warm enough and started idling like crap... That horrible miss that I cant get past under any amount of revving.

I started spraying brake clean on a couple different sensors to see if they would make the car run normally after being rapidly cooled... TPS, IACV, MAF... Nothing. I ran the car with the TPS unplugged, no change, no change with the maf un plugged, no change with the IACV unplugged..

I'm pretty much lost, I'm nearly convinced the Ignitor is fine.. The ignitor signals the firing order of coil packs, and its doing just that.

I'm stumped.

[Sil240]

Is that really a safe thing to do???

Umm why don't you do the ghetto hood mod.Stick some washers under the bolts of your hood.Get some air flowing under there.Or cut your hood and mesh it.Ghetto mods.

[DriftingisLame]

the brake clean only contacts the outside plastic cover of the sensor, cooling it off hella fast.. I know a guy who was a mechanic and an airplane tech, and he suggested that to me to diagnose intermittent heat related sensor problems.

I will do the hood mod but that really doesnt help anything right now.. Just take 2 minutes longer in the morning for the thing to start running like ****.

[DriftingisLame]

Still looking for suggestions, thanks

-Max

[rotorimp]

When the car is cold, it is in open loop--meaning that there are certain sensors that the ecu does not use until the car is warm. So if your car runs good up to a certain eng. temp then I would concentrate on those sensors. The O2 sensor is one as well as the temp sensors. Measure the signal produced by the O2 sensor--is it in spec? Is the gage on the inst. cluster where it usually is? Heat can still do weird things to car components--How was all the wiring done in the car--(all soldered w/ heat shrink or were they butt connected or twisted together with electrical tape?

[DriftingisLame]

Everything was soldered.. A section of my gauge cluster is very slow and is not accurrate, that includes water temp, fuel, warning lights (dim)... I dont understand why, but I have an aftermarket water temp gauge, thats what I go by.

I had a brand new o2 sensor laying around so I threw that in and it didnt fix anything.

I'm still getting a maf code and knock sensor code.. Everyone I talk to tells me my maf is the problem, and I just dont understand why it would be the maf, it doesnt make any sense to me at all.

How do I test a knock sensor and would a knock sensor cause this problem? My car is starting to depress me, any help is appreciated immensely..

Thanks gangsters-Max

[roadrunr]

I'm still learning about these engines but I know that my Mazda Speed3 has a Ambient Air Sensor that reads the air temperature and adjusts fuel density based on the readings, not sure if these engines have one but that sounds like what your car is doing, starving for fuel. Like you said, in the cold dense air of oregon and when cold its fine, but once it gets warmed up in the hot thin air of phoenix, it starts acting up. It kinda seems like it never changed settings from Oregon to Arizona as far as your A/F ratio, OR the new water temp gauge you put on is interfering with the ECU's readings.

[skillzilla]

Yeah that is what I was thinking as well. Dumb question: You reset the ECU or it got retuned (if it was in OR) after your move, right?

[DriftingisLame]

The water temp sensor is not routed into the ECU it goes to a completely separated gauge.

I drove the car normally here for about 2 months, other problems include : coil pack that missed when it heated up, and blew a couple heater hoses.. Its ran fine since I've been here other than that.

Resetting the ECU sounds like it would make a difference but not exactly something this extreme, you know what I mean?

[roadrunr]

You definitely have a strange problem, I was still gonna say maybe the fuel filter is clogged but then it wouldn't run good anytime. I did notice a Troubleshooting section in the FSM that might help out, I really feel for ya man, I hate it when things like this pop up and ya just can't get a handle on it, I'll let you know if anything else comes to mind but try the FSM and see if you run accross anything there that might help. You might also ask Greg, AzHitman, he's knowledgable about these motors, and lives here too.

http://nicoclub.com/FSM/rb

[klh6686]

The water temp sensor is not routed into the ECU it goes to a completely separated gauge.

I drove the car normally here for about 2 months, other problems include : coil pack that missed when it heated up, and blew a couple heater hoses.. Its ran fine since I've been here other than that.

Resetting the ECU sounds like it would make a difference but not exactly something this extreme, you know what I mean?

This is true, but the Engine Coolant Temp sensor runs to the ECU, checked it?

[roadrunr]

One other thing did come to mind, air in the fuel lines. I also was browsing the web today and some of the aussie sites have some good troubleshooting info on them, I just ran a google search for "rb25det install" and got all kinds of hits, maybe you can find the answer there.

[rotorimp]

I know that you installed a aftermarket temp gage. Does the ecu get a temp signal? If your ecu does not get the temp info then it WILL have the problems you described.

[DriftingisLame]

Well.. The temp signal is now routed to the ECU. I finally hooked it up after a massive brain fart when I did my wiring in the first place. The car ran fine and drove without problems for probably 8 months before I realized it wasnt hooked up... So I dont see how that could possibly cause such a massive rpm specific misfire. Its been wired in for 4 months now

Air in the fuel lines seems like it could be the cause, but that would be a little more sparatic dont you think? This is very specific, after the motor soaks for a while in about 200 degree farenheit coolant, if the rpms drop below 2000, the car stalls, with no saving it... throttle is useless, as is trying to start the car immediatly afterwards. Wait 5-6 seconds and start the car and it will catch, but have a what seems to be ignition miss untill you rev past 2000 rpm.. Once past, the motor will run perfectly, but if you let go of the gas before it reaches 2000 rpm, the motor dies with a vengance again.

[rotorimp]

Still sounds like a fuel problem. When the motor is cold the ecu adds more fuel because it is harder to ignite when cold. if the ecu has the WRONG motor temp it could be adding more fuel and stalling out the motor. A motor will sound/run better at higher rpms even when it is rich (your AFR will reflect it). We have gone over boost leaks and temp problems--There is no way you have air in the line--you could have low or high pressure but FI cars will not run at all if you can't pressurize the fuel system. If your getting MAF codes look into that some more--see what voltage the ecu is getting. TPS also can cause rpm specific problems--ohm it or check the voltage sweep at the ecu (prefered). Is the car wired for consult?

[AZhitman]

^

[DriftingisLame]

I dont believe the car is wired for consult, and I'm not entirely sure how that program works, but I am very interested!

If the TPS was sending a bad signal to the ECU it could cause something like this, but my SAFC intercepts the TPS signal and it reads pretty accurately.. Should the TPS still be a concern?

I sprayed carb cleaner in the intake while the car was horribly studdering, to see if perhaps this was a fuel related problem. I figured that if the idle changed, or maybe the motor picked up a bit it was because the carb cleaner was compensating for the lack of fuel... Definately didnt change anything. Still studdered horribly..

The CAS is what determines ignition timing, and injector firing order correct? I'm not exactly what in the CAS could fail depending on tempurature, but could this be a concern?

[skillzilla]

Rotorimp mentioned a rich condition, not a lean condition. Spraying carb cleaner when it is stumbling would only add to the problem. How are the plugs after a good bit of driving? Pull them out after the problem surfaces one day and see if they are wet, burnt, etc. That will tell a lot about the fuel situation.

Also, have you reset the ECU to at least clear the codes and see if that helps anything? Also, like Carl mentioned before, check the ignitor to see if the higher heat is killing it. I had an ignitor on the fritz and it caused headaches for weeks.