I'm having an issue where my engine cuts out at certain RPMS at WOT, but the RPMs vary based on what gear I am in. Not sure if fuel is getting cut, but it won't go past a certain RPM. So for example in 2nd gear it will cut out at around 7k RPM, in 3rd it's more like 6500 RPM. If I partial throttle it, it will go past those RPMs, only happens at WOT. Not super familiar with the car/setup as I am not the original owner.
Here is my setup:
B18C5
- 12.5:1 pistons
- Skunk2 Tuner 2 cams/springs
- P28 Civic ECU with chip
- Apexi V-AFC (zero'd out fuel maps)
- Upgraded fuel pump
- Aftermarket fuel rail with FPR (I think it pressurizes to 60PSI)
- Stock injectors (I believe, I was told they look like it)
- GS-R header/down pipe
- Aftermarket Cat
- Revel (Tanabe) Medallion Touring S CBE
- Stock Intake

Any help is appreciated!

 

Engine load increases with higher gears, so the symptom that you describe comes from one of two problems: A weak coil or ICM inside the distributor, or a fuel system issue causing a progressively leaner condition as engine RPM increases.

 

Thanks for the reply JRCivic1. It revs perfectly fine the whole way (and past VTEC), it is an abrupt cut of power. How do I check for a weak coil or ICM?

 

Try a known good distributor. You can follow the diagnostic flow chart in the FSM to test the coil and ICM, although if you are suggesting you experience a "hard cut" instead of a stumble/studder that gets worse as engine RPM climbs... it may not be fuel or ignition related. Have you checked your TPS for a full sweep of voltage (.500v at throttle closed, and between 4.20 and 4.60v at full throttle) ? Also, check to make sure you don't have any wiring issues with your V-AFC. It has been 20 years since I used one of those... you might consider some engine management and a good tune instead of that dinosaur too.

 

JRCivic1, is the V-AFC sensor check accurate for testing the TPS? If so, it reads ~.4v (closed) and ~4.6v (WOT).

 

4.60v should be just fine for full-throttle operation. It may not fix your issue here, but you should really consider ditching the V-AFC and getting engine management. At least this way, you would have live data to examine to help diagnose what is actually happening. For example, lets assume that you actually have a bad tachometer and the engine is running perfectly fine. You could see this in the data stream... you would reach the set redline in each gear, but you would see a different value on the tachometer.

(You may be able to test that theory with the V-AFC... doesn't it have a tachometer reading on the display screen ?)

 

Here is my dilemma, the car was modded from 2 owners ago and the previous owner doesn't really know the details other than the list of parts that was provided to him. The car runs really well other than the issue I am having. I considered putting a Hondata S300 in it, but then I would definitely have to get it re-tuned and there aren't any tuners in the general area. I would prefer to fix the issue I have and use the current tune that is on the chip. I am thinking of pulling the V-AFC to see if that changes anything since the fuel maps are zeroed anyway, not sure if that would prevent VTEC from engaging (it is set at the stock ITR changeover) or perhaps it is set on the P28 ECU? I ordered a replacement coil to see if that changes anything, but from what you say it probably won't. The tachometer is working properly because I can see the VTEC engagement point cross over at the same RPM and the cut off happens not too long after and the engine doesn't rev anyway near the 8400 redline. I can check the V-AFC just to be sure, but you can hear that the sound of the engine isn't high as it should.

Could the injectors be an issue? Isn't there an injector resistor box that is near the driverside fender (has cooling fins), what does that do? Thanks again, I appreciate the help!

 

JRCivic1, I swapped out the coil and have the same results. Just another data point.

 

There should NOT be a fuel injector resistor box connected to the engine harness over on the drivers side corner of the firewall UNLESS the fuel injectors that are installed in the engine are Low Impedance injectors. Check the OHM resistance of each of the four injectors with a multi-meter... Low Impedance would be between 1.5 and 3 OHM. High Impedance will be 10 to 16 OHM. If the fuel injectors are High Impedance, you should not have a resistor box. If you remove it, this changes the personality of the tune and now the car will not run appropriately with the tune you currently have on chip. You WILL NEED TO REMOVE IT. In addition, you truly don't know what the tune on the chip does... and if the V-AFC has any influence at all on the car.

If I were you, I would get your P28 ECU upgraded to a Hondata S300, remove the V-AFC, and get the car properly tuned. If the symptom persists, you will have removed any unnecessary variables AND you will have data available through your engine management to help you "see" what is happening at any given time.

 

I believe the injectors are stock, which should be low impedance? Would you be able to tell me if they are stock if I posted a picture? I can check the resistance when I get time during the week.

 

JRCivic1, I checked one of the injectors and it read ~2.6 OHMs. Could the resistor box be an issue? I could remove the V-AFC as the next step since the fuel maps are not doing anything. If I were to get a S300, do they make basemaps that are safe, or do you always need to get it tuned? I think the whole purpose would be to get it tuned, the issue is I don't know anyone around me that tunes these old Hondas.

 

You will have to get the engine tuned... there is no "basemap" in the Hondata library for an engine with the exact same mods as yours.

 

Could it be an issue with the resistor box? Trying to search for symptoms of it going bad but I can't seem to find any.

 

The resistor box just puts resistance in the 12v power wires going to the four individual fuel injectors... failing resistor boxes usually show symptoms of losing voltage at particular cylinders or shorting out... either way, the fuel injector (or injectors) stops working and you have dead cylinders. It doesn't cause lean conditions at high RPM.

There are tune related possibilities that are beyond your ability to check/verify... you do NOT know what is burned on your chip and you don't know what program was used to create the calibration for the chip. Getting a modern engine management/tuning solution will provide you with more information... and then you can provide this community with more information so that we can better assist you in diagnosing/fixing your problem.

Help US help YOU... get rid of the dinosaur **** and join 2025 !!!

 

Where are you located ? Depending on your location, I may be able to refer you to a capable tuner.

 

I'm in Harford County Maryland (Northern Maryland).

 

Sorry, I don't know of any tuners up in the Northeast that I would recommend. Derek @ IMWTuned is probably the closest to you that I know... and he is in PA.

 

They are about an hour and a half away and according to their website, Hondata s300 tuning is a discontinued service. To be honest, I really don't care about making the most power, I just want it to run right, safely.

 

Any harm in using the stock ITR ECU to see if it nets the same result?

 

My car appears to be working! I had purchased a custom chip for my P28, which ended up not working so I ended up putting the original chip back in. Perhaps the jostling of the wires in the harness or the seating of the chip made a difference? No idea!

 

Glad to hear you got things worked out.

 

Thanks for all your help JRCivic1! I haven't messed with this type of stuff since I had my '00 Prelude Type SH JRSC back in '03!