Comptech S/C - Partial throttle issues

audioserf · 05-04-2009, 08:40 AM

If you saw my other thread (Dyno Disappointment), you'd know I was getting a constant P0325 - Knock Sensor CEL. Well, I had a new knock sensor put in at Excelerate on Saturday, and that took care of those codes. Looks like it was a bad sensor after all.

However, I'm not out of the woods yet. The car pulls hard and wants to run - as long as I'm going WOT through the gears. If I'm riding partial throttle in boost (say 5500-6000rpm, particularly in 3rd and 4th gear), I get a flashing CEL. The Excelerate crew thought this was misfire caused by bad gas. I ran the gas tank out and refilled with Sunoco Ultra93, and I'm still having the issue.

Am I getting misfire? Since it's a flashing CEL, I don't know what the code is (it's not storing), but it's only coming on at partial throttle while in boost. When this happens, the car gets VERY jerky, ie if I lift off the pedal, the car lurches forward a bit.

Since this is only happening at part throttle I'm assuming it's a fuel issue... but if that's the case I'm not sure what can be done about it given I'm running the Hondata S/C Reflash, and nothing's been specifically tuned on our end. Could I have been given a bum Comptech ACM (since I understand that controls boost, fuel, and the MAP sensor)?

Other relevant mods:
Injen CAI
Topspeed header
RT Cat
Tanabe Catback

Things we've checked:
belt tension
sparkplugs
fuel
knock sensor

HELP!

- Matt, sick of the nightmare that has been his boost experience thus far.

a2dadamm · 05-04-2009, 08:52 AM

oh manzzz,

it wasnt doing any of that ever before the install of the s/c right?

it sounds fuel related deffinatly, im not sure it would be bad gas tho, try and contact competch and explain to them whats going on and maybe they can help you out,

good luck man, this whole situations sucks, especially after you spent a decent chunk of change..

audioserf · 05-04-2009, 09:09 AM

Yeah, none of these issues ever happened prior to the s/c installation.

xjohnkdoex · 05-04-2009, 11:00 AM

have you tried posting this in the hondata forum? they seem pretty responsive there if you have a question/problem. man, sorry for the issues. glad you got the sensor figured out.

audioserf · 05-04-2009, 11:15 AM

I actually just shot Doug @ Hondata an e-mail. I'm hoping he's got some ideas. But I may hit up the Hondata forum if he doesn't know what's going on.

Jeremiah · 05-04-2009, 11:34 AM

Are you running stock injectors?

I ran into many issues when I turbo'd my 98 accord, and they were all ecu issues, no mechanical issues. You are also running the stock fuel pump, right?

(Not real sure about the requirements for the comptech setup to run correctly, just throwing questions out there)

Also, just curious, why are you at partial throttle at 5500 rpm?

xjohnkdoex · 05-04-2009, 11:44 AM

i think the S/C kit comes with its own injectors if i remember correctly.

audioserf · 05-04-2009, 11:56 AM

Quote:

Originally Posted by Jeremiah

Are you running stock injectors?

I ran into many issues when I turbo'd my 98 accord, and they were all ecu issues, no mechanical issues. You are also running the stock fuel pump, right?

(Not real sure about the requirements for the comptech setup to run correctly, just throwing questions out there)

Also, just curious, why are you at partial throttle at 5500 rpm?

Stock injectors -- CT kit doesn't include upgraded ones. It uses the stock ones (albiet to near their max capacity). I plan to upgrade to larger injectors when I can afford KPro + tuning. I believe the Comptech ACM works in conjunction with the reflashed ECU to control fuel.

As for the part throttle at 5500, I first discovered the CEL when I had downshifted from 5th to pass someone, but then wasn't able to (another car moved in the way) so for a couple of seconds I was sitting at that point in the powerband, and noticed the flashing light. After that I was easily able to replicate the issue, so I figured I should see what was causing it.

DAYTA · 05-04-2009, 12:31 PM

I also experienced a bucking issue with partial throttle in the 5-6k rev range when my S/C was first installed. It could be a DBW/fuel delivery issue with the reflash mapping, possibly inconsistent injector spray patterns since the OEM injectors are at near max duty cycle in the higher RPMs. Unfortunately, there isn't much you can do about it. I dealt with it for over 1 1/2 years before going K-Pro. However, I never threw CELs so your problem might go deeper.

Btw, you shouldn't really need to downshift to pass someone given the great midrange you get from the S/C (especially since it sounds like you were around 4k in 5th). Old habits die hard

.

audioserf · 05-04-2009, 01:17 PM

Haha, that's true.

Josh is going to get on the horn with CT-E about having a replacement ACM sent out, just in case mine's faulty. If nothing else, it will rule out another potential cause of the problem.

This is feeling like a never-ending story.

Jeremiah · 05-04-2009, 04:34 PM

It may feel like that... but it will all be worth it when it's working good.

audioserf · 05-04-2009, 05:37 PM

Well, I reset my ECU and the flashing CEL seems to have stopped. The car still bucks when you let up on the throttle between 5500-6500, but that seems to be a "feature" of DBW interacting with the reflash/ACM more than anything. It falls in line with DAYTA's pre-KPro experiences.

I'll be keeping an eye on it for a week or so before heading to the dyno again.

neoryan7 · 05-04-2009, 08:21 PM

In the kmanager you probably have the "Illuminate CEL when knocking checked" So whenever you have knock it flashes. Dayta probably doesn't have this option checked off.

That's why it doesn't store codes.

audioserf · 05-04-2009, 09:07 PM

Quote:

Originally Posted by neoryan7

In the kmanager you probably have the "Illuminate CEL when knocking checked" So whenever you have knock it flashes. Dayta probably doesn't have this option checked off.

That's why it doesn't store codes.

I'm actually not on KPro though -- I'm on the Hondata reflash provided for the Supercharger. So I don't think it uses a flashing CEL to indicate knock, unless I'm mistaken. I e-mailed Doug @ Hondata explaining the problem, and in his response to me he didn't mention anything about the flashing CEL meaning knock.

Tsx536 · 05-05-2009, 02:11 PM

Hey Matt,

The flashing CEL does indicate knock with the SC setup. That's why no DTC codes were stored. You were getting knock. I ran into the same thing before with the SC setup. It would happen if I downshifting, was heavy on the throttle, and then all of a sudden let go. This seems to cause knock. I think this is because you have a lot of load on the engine, manifold pressure is built up in the manifold, and then all of a sudden you let off but the pressure is still there.

Not sure if that's the exact cause but I noticed it would only occur if I was at high RPMs and a had heavy load on the engine and suddenly let off the gas. I learned to let off the gas more progressively. Am I'm not sure if the ECU eventually learned because I didn't run into that issue in the last year or two. So anyway, this isn't a show stopper. Just try to transition more smoothly off the throttle if you're in a similar situation. I eventually learned to not get the engine reved up like unless I was for sure ready to go. Just get over and wait an extra second before getting on it, you'll be leaving those cars in your rear view anyway