Daonlyone74

I have a ek with a ls vtec motor that's race on a track. This isn't a daily car at all. So the problem we have is coming out of the turn getting up to around 6000 rpm th car starts t miss and sputter like it's loosing spark. Happen s after 2 or 3 laps and the car is warm.

This is what I've done. Rented the track and tested things out. Put brand new dizzy and wires and plugs on car. Car still acted up. Brought it in and swap ecus car acted up again after a lap. Put new tb on with new map and tps and car still acted up. Then I unplugged vtec and car acted up again. I then decided to unplug the coolest temp sensor under the vtec solenoid. And went out and nothing happen car ran fine got it up to 8000 no problem (but vtec didn't work because coolent sensor was unplugged) . Plugged the coolest sensor in again with vtec still unplugged and it missed up. Plugged vtec in with coolent plugged in and messed up. Unplugged coolent sensor one more time and the car ran perfect didn't mess up once.

Is this really the problem the coolent temp sensor? Didn't know that could do this to a car. It almost seemed like the ignition coil was getting hot and shutting off at high rpms but we ruled that out. Any I'm put would be great thanks.

DarryCar

Change the coolest temp sensor. ECU checks that input and basis it's parameters off of that and all the other sensors. Easy fix, give it a try.

Daonlyone74

That's what I have done I replaced the coolant temp sensor. I'll let ya know what happens at the track Sunday

Daonlyone74

I replaced the coolant temp sensor and the car did the same thing after about 4 laps around the track. Any ideas?

Daonlyone74

I've replaced plugs, wires both ngk, new dizzy from autozone. Swapped out fuel injextors and went through the entire wire harness to look for broken wires nothing. The car runs great for 5 laps and then has then hits 6k rpms and won't go more. I've swaped ecus and that didn't fix it either. Any ideas would greatly help.

DarryCar

What is it doing? Does it sound like it is bouncing off of a rev limiter or something? Do you have a VTEC controller or anything to piggy back the ECU?

Daonlyone74

I have changed ecus and used my s300 to data log it. When the car messes up after the 5 laps you can see the rpms go up steady and then the line gets super choppy at 6k and goes up to around 6300 and back down but it happens very fast like a rev limiter but at 10 times the speed. You hold the gas down and it just doesn't do anything. Until you get lower in the rpm range. Step on the gas again and sec it gets up to 6k same thing every lap after. Let the car sit fr a while and you can run another 5 laps and it happens again.

Daonlyone74

It does it with vtec unplugged also so it nothing wrong wth vtec or ecu cause it did it with my s300 and the chipped p28 running different tunes. The s300 just had a quick base map on it.

DarryCar

What is the rev limit set at in the s300?

Daonlyone74

Rev limiter was set at 8750

Daonlyone74

It sounds like an ignition miss like bad plugs but all that is brand new. Just doesn't make sense that it happens after 5 laps of running perfect all the way to 8700 rpms.

DarryCar

I would contact Hondata through their forum and see what they have to say. They can be pretty helpful.

ShinsenTuner

iTrader: (1)

What is the temperature with the coolant temp hooked up? VTEC needs to verify temperature in order to engage. Your datalog should show this.

Daonlyone74

Temp is 185 across the board. Vtec engages fine that isn't the problem. The problem occurs with or without vtec vtec

Daonlyone74

Today I replaced everything inside the distributor with all honda oem parts. I also put in new injectors and a fuel pump. The car missed again tonight after 4 or so laps. Anyone got any ideas. Car was running first and fell back to last because of it.

Calif_Kid

Since the problem only showed up after 4-5 laps, I was thinking of the possibility that the oil pressure might not be as high as the oil got hot, and if the oil pressure was low enough, then VTEC might disengage. The thing is, that you mentioned that you already tested and figured out that VTEC wasn't part of the issue, so what I'm mentioning shouldn't be causing it.

When the car misfires, does the misfire happen all of the way around the track or just in the corners?

PS - you mentioned that when unplug the coolant temp sensor under the vtec solenoid, you went out and nothing happened and the car ran fine got it up to 8000 no problem (but vtec didn't work because coolent sensor was unplugged), so you ended up putting in a new coolant temp sensor, but are still having issues. Is there maybe something messed up in the coolant temp sensor connector or wiring to the ECU that is affected by the engine temp? - Jim

Daonlyone74

Yes the oil pressure is good and correct the car did also do it with the vtec function disengaged. The car does this miss when he his coming down the straights the car gets t around 6k rpm and has like an ignition miss like bad plug wires. The car doesn't go over the 6 k mark. I want to see if I can upload a video of it happening.

Calif_Kid

Just wondering - when the car starts missing out on track, have you tried leaving it running and checking for any codes in the Hondata S300? Also, I've heard that the S300 can log parameters (but I've never tried doing that), but have you tried logging various parameters (ECT, IAT, etc...) out on track? Is the 185F for engine coolant temp directly from S300, or is it from a gauge on the dash? - Jim

Daonlyone74

Yes I had t hooked up to my laptop on the s300 and did datalog the car while running, You could see where the car had the miss by the rpm line it ad a stead graph going up and down and then when the car misses the line went up to arould 6k prm and the line got super choppy not going over 6200. like it was hitting a rev limiter. The s300 didn't show and codes and the 185f was the engine temp that the s300 was reading the entire time the car was on the track. the temp sensor is new, plugs wires all dizzy componets fuel pump injectors is all new. wire harness was gone through I dint see any breaks in wire or anything. engne grounds are good.

Daonlyone74

This is the graph you caan see on the bottom graph at 2:30 to 2:50 the car messed up twice. Rpm are very jumpy.

Daonlyone74

This is a second run i did. Ssme thing at 1:45 the car meesed up 3 times untill 2:10.

Calif_Kid

I've never read logs before, but I had a few quick questions/comments:

1) If I read the logs correctly, it looks like the TPS goes up to max normally, but when the car misfires, it doesn't go up that high plus has quite a bit of oscillation/noise. If the TPS was working correctly, then even if the car started misfiring (from fuel or ignition etc.), then shouldn't the TPS reading be unaffected assuming that you had the throttle completely pressed?

2) Is the fuel injector duty cycle max on the graphs 100% ? If it is, then when the car misfires, it appears that the duty cycles don't go as high as they do when the car is running correctly. I'm assuming that something else may be causing the misfire and the lower duty cycles are a result of that. Also, if the duty cycle is actually going up around 100%, then I thought that the injector sizes were supposed to be chosen to keep the max duty cycle at some lower value.

Again, I'm not familiar with logging plus the details about the ECU and sensors etc., but just wanted to see what you thought. - Jim

Daonlyone74

See I also don't know much a out reading the graphs. I sent the logs out to a couple places thinking that a tuner would be able to spot my problem and I'd know what's happening. One shop tols me about the injectors running a high duty and to swap in another set. That maybe the injectors where burNing out. I did that last week along with a new fuel pump and it didn't help. I tested the tps and the test cam back good the tps has a good sweep from closed to wot.

Daonlyone74

And I see what you mean about the tps should still be going up smooth to the max since the gas is pressed. Now I wonder why it gets all jumpy like the rpms do.

Calif_Kid

Last night, I did a quick search for 'bad TPS' posts, and some had info on what the voltages should be at closed and full throttle, which it sounds like you have checked. I'm not sure if a TPS could have issues when it gets hot though. Some of the posts also mentioned checking the connector or especially the wire(s) from the TPS to the ECU. If you think that the TPS unit itself might be an issue, and can't see anything obviously wrong with the wires or connector, then maybe you could put a spare throttle body with TPS on, and see if it fixes the issue.

For the wires from the TPS to the ECU, maybe you could test it by having the key/power on (but engine not running), and if the S300 manager will display the info with the power on but engine not running, then have the throttle full depressed and watch the TPS value, and then wiggle the wires/connector to the TPS and see if the TPS reading on the S300 manager screen changes.

One other thing I saw mentioned quite often, was making sure that the MAP and TPS connectors aren't swapped, but if that were the case, I don't think that that explains why the car runs fine for 4-5 laps and then has issues. - Jim