Turbocharged K20A2 swap cuts fuel at medium load

D-Rob · Post by **D-Rob** » Tue Jul 22, 2008 2:39 pm

Recently, we have completed a friend's turbocharged K20A2 in a 1995 Civic hatchback.

Upon driving, the car seems to cut fuel at medium load (between 13 and 10 inches of mercury), and unsettles the car.

Adding an immense amount of fuel in the problem area has zero effect on the AFR.

We have tried numerous calibrations, various cam angle adjustments, etc... and still to no avail. Lastly, as an experiment, we swapped out the ECU for another known good one from a vehicle at the shop, loaded the latest basemap, and the problem was gone, and the car drove normally.

Could this be a hardware malfunction?

- Derek

EDIT: I have attached the datalog. The problem area occurs at around 2 seconds, 11 seconds, and at 40 seconds.

Post by **Spunkster** » Tue Jul 22, 2008 5:09 pm

you need to also attach the calibration

D-Rob · Post by **D-Rob** » Wed Jul 23, 2008 5:12 am

Calibration added.

- Derek

Post by **Hondata** » Wed Jul 23, 2008 8:20 am

If you put the exact same calibration into two ECUs, and one doesn't work, then it is the ECU. The datalog looks ok apart from a voltage issue - the battery voltage jumps around a lot, as does the ELD and sensor readings.

D-Rob · Post by **D-Rob** » Wed Jul 23, 2008 8:36 am

I am loading the calibration onto another K-Pro ECU this afternoon.

And I thought the same, concerning the voltage. Is there any battery voltage corrections that could be wreaking havoc on the system?

Maybe a revamping of the charging system is in order.

- Derek

D-Rob · Post by **D-Rob** » Wed Jul 23, 2008 12:19 pm

We swapped in another ECU and loaded the calibration.

Same problem, so that leaves out the possibility of a hardware issue.

We have now narrowed the problem down to 3,000 RPM, regardless of load after a couple tests.

- Derek

Post by **Spunkster** » Wed Jul 23, 2008 2:07 pm

It may be a problem with the fuel sisytem, or some kind of wiring problem. Anytime you ahve an engine swap it makes diagnosing the problem much more difficult.

D-Rob · Post by **D-Rob** » Wed Jul 23, 2008 3:27 pm

Spunkster wrote:It may be a problem with the fuel sisytem, or some kind of wiring problem. Anytime you ahve an engine swap it makes diagnosing the problem much more difficult.

I added a ridiculous fuel value at the problem area, and the problem was less noticeable, but AFR still went as lean as 20:1.

6500 units of fuel on that calibration at the 3,000 RPM, 15-10 in-Hg load point makes it better, but every value around it needs to be in the 600-700 range to be anywhere near the proper AFR.

I may try swapping out the Precision 1000cc's out for some DSM 450's just to eliminate the injectors as a variable.

Also, I am pulling the alternator tomorrow in search of the voltage regulation issue, as the voltage bounces down to 12.9v when the problem occurs, and bounces around from 13.1v to 14.2v when under or over that problem area.

Thanks for the help so far. :)

- Derek

D-Rob · Post by **D-Rob** » Sun Jul 27, 2008 1:34 pm

Alright, the injectors have been swapped out, the coilpacks have been changed, fuel pump checked, and still at that RPM/load point, there is a a noticeable fuel and/or spark cut.

Are there any known problems I am not familiar with having to do with the older Hybrid Racing swap harnesses?

Also, the alternator has been switched, yet the datalogging still shows the fluctuation from 13.3v to 14.4v. BUT! When tested for voltage at both the fuse box, alternator, and battery, voltage is a constant 14.4v, with no fluctuation. Could it be a bad power supply to the ECU? If so, what pin location does K-Pro use to datalog battery voltage?

- Derek

Post by **Spunkster** » Mon Jul 28, 2008 10:38 am

I would suggest trying yoru ecu in a known good vehicle (one that is preferabley not an engine swap) and see if the problems go away.