Hello all,

Taking a bit of a stab in the dark here but I finnaly got my car running (1975 Mini Cooper w/ 1998 GSR b18c1 & p72 OBD2a) and I am in need of learning a bit about tuning ECU's.

Here's what I think I know so far;
- Engine is stock. Skunk 2 replica IM & exhaust header.
- IAB, post-cat o2 sensor, and secondary butterfly system are all gone.
- Car runs at high idle when cold, after warming up a bit, car surges from its high idle to a lower idle. Presumably because of the missing sensors.

Surging at the end of the video.


Researched a bit about hondata and similar products and it seems that switching to a chipped OBD1 ECU is the only option. Is this correct?

 

Easiest/cheapest would be to convert to obd1 and tune with crome

 

And at the very least you'd need to switch to OBD1 to deal with the missing sensors. You could try a stock OBD1 p72 ECU, or if you wanted to tune there are lots of options but all require OBD1. Getting an OBD1 ECU on an OBD2 engine is easy -- you just need a conversion harness to connect the OBD2 harness to the port on the OBD1 ECU.

 

Yes, convert to OBD1 with a conversion harness. If you wish to retain closed loop you'll only need the front O2 sensor.

Check out NepTune at HRTuning.com. You can download the software for free to check it out.

 

In the essence of saving a little time, was thinking about purchasing a prechipped OBD1 ECU. (also dont have very good soldering equipment)
Something like this.
http://www.xenocron.com/chipped-obd1...19366212730182
Says it comes with a custom basemap chip. I assume this is where I would specify the modification I have made to the engine and they would burn the chip accordingly?
As far as tuning software, I assume its USB to the ECU? Or do you have to remove and reburn ROM chips like on my camaro?

Thank you for your replies.

 

besides the swap itself, what have you done to the engine?

for tuning you need to get:
OBD1 Vtec ECU you linked above (or similar)
Crome http://www.tunewithcrome.com/
Chip Burner http://www.xenocron.com/burn2-usb-chip-burner-p-88.html

And if your planning on dialing in AFR further than a stock map (depends on what is done to engine) It would be a good investment to get a Wideband.

 

You're correct about the custom tune, but I'm not sure whether it's necessary. You could pm Xenocron here and he'd give you a straight answer.

Your cheapest and easiest options by far are to either get a stock OBD1 p72 ECU, or to get a chipped ECU from a place like Xenocron.com or Phearable.net. In that case you wouldn't be getting a GS-R ECU, but would be getting one that was modified with a VTEC circuit enabled. You would then chose whether you wanted a stock basemap or a custom one. Both Xenocron and mtber (Phearable.net) are honest guys and they wouldn't sell you a custom chip if you didn't need one.

 

Thank you very much gentleman for your help.
I will get on this ASAP! Cant wait to get Frogger on the road (legally )

I PM'd Xenocron.

The engine is bone stock besides the IM and exhaust header. I figured 150+ HP in a 1400LBS gokart was goin to rock my fun-o-meter for a little while

 

Missing secondary o2 or butterflies wouldn't not cause that surge

My guess is a throttle body issue, gasket on incorrectly, too much sealant, throttle body stop or set screw not set correctly, dirty iacv....

I doubt just switching to obd1 and a basemap will cure it, but it might

 

Well I'm almost embarrassed to say this but the IACV connector was dangling behind the motor. In all the assembly I forgot to connect it. Good thing is, now it’s connected. Had to lengthen the wires about 12" but they reach now.

New dilemma... after connecting the IACV, car is idling ridiculously high (probably around 3000-3500 RPM's. Still have not cleaned the IACV, will do that tomorrow.

I had a question floating around in the back of my mind a while ago. Will running the Walbro 255 pump with a stock FPR cause any strange problems?

 

No it won't.

Is there a fast idle valve on the bottom of the throttle body?

If so, that might be part of your issue

 

FITV thread:

https://honda-tech.com/forums/honda-crx-ef-civic-1988-1991-3/how-fix-fitv-its-easy-1-2-3-a-699787/

 

Doesnt seem to be a FITV on the car. Engine was from a 98 and I believe they stopped putting them on in 96?

Ashamed to say that I still havn't cleaned out the IACV, been stuck at school and work with no time. Going to go home and do it quick after school today.

Found this post in a thread on the integra forum. Makes some sense to me.

"IAC(v) stands for IDLE air control (valve)

this IS whats making your car idle higher, and theres absolutely nothing wrong with it. when a car starts when its cold out, the IAC senses real cold air coming in so it adjusts the the idle (throttle) accordingly, which results in giving it more fuel. it also does this because when a car first starts the O2 sensor isnt hot enough (300 degrees farenheit) to get a signal. this signal tells the ECM whether the engine is running lean or rich, so the PCM guesses on what would normally be a good air/fuel ratio which results in a high idle. pretty much your ECM tells it to idle high, so the engine can get up to normal operating temperature, ie the O2 sensor, so it can run properly. theres the pretty thorough explaination to anyone, on why your car idles high when you do a "cold start" and this is standard with any car."

May let the car warm up a bit and see if it settles down.

 

There is no FITV on GS-R engines, except maybe the 1.7L. I think many people with IACV problems get a roaming idle during warm up but not necessarily when the engine is at operating temp.

 

96+ b series with a manual transmission had no fitv. obd1 did.

 

I thought it was only OBD0 that had the FITV on manual-equipped cars. Sorry for the misinformation

 

Let it warm up today until rad was warm to touch and IACV was also warm to touch, nothing changed. Tried unplugging the IACV and idle goes back to surging. If the TPS is unplugged, surging goes away. Checked TPS reading and somehow it must have gotten bumped. Reading was .66v
Reset TPS to .50v and it ran good for about 45 seconds and then start a very slow surge. Also noticed with the key on, engine off, the IACV makes a low pitch humm. Not exactly sure if thats normal.
VID:
http://www.youtube.com/watch?v=Yc-X3...ature=youtu.be

For some reason the video looks like its in slow motion, stupid youtube stabilizer...

I checked continuity from the IACV plug to pin 35 and thats good so I don't think I have it hooked up to the MAP sensor wires.

My engine is from a "running" car here in the US. Has the 4 wire O2 sensor connector w/ heater.

Still need to sort out the wiring to hook up the cluster and read the CEL.

 

did you bleed the cooling system?

 

I have not, wasn't aware that it needed bled. Any other obvious procedures like this that I may have missed?

 

Exactly what I was thinking. Also make sure you don't have any vacuum leaks. This is what Xenocron was referring to as far as the gaskets.

 

Can't seem to find any literature on how the bleed the cooling system. Everything I read says to fill the rad full, run it and fill it again when cool until its full.

Can someone point me in the right direction?

Also, will check for vaccum leaks. Must be a hole somewhere I'm missing.

Thanks

 

Alright, didnt want to start a new thread so Ill post here. Sorry its been a while.

Changed the OBD2a P72 to a chipped P06 w/ b18c1 basemap.
Tore the IM apart and replaced the IM gasket and retorqued 5 ft/lbs tighter than recommended. Looked at the TB gasket close and it didnt seem to be sealing the IACV so I made my own.





still leaking
vid

Checked codes after running for a good 20 minutes and got two long flashes. not sure what that means.
WTF is going on here?

 

Ok, went out a figured something out just now.
The whistling is coming from the valve cover breather hose pulling air through the engine when the intake is blocked off. That's why the engine remains running even though I "thought" I had choked it out. Unhooked it and covered the intake (for the last time) and hose port and it died right away like it should... Got to be a sensor right...?
Set the TPS to .5v like specified in the manual. Tried 2 different IACV's with the same results. What else is causing this?

 

Have you bled the coolant system? Have you adjusted the idle on the TB? Cleaned out the TB and intake manifold?

 

Cooling system does not have a bleeder valve (some engines did, some didn't), I checked that a while ago. I have let it warm up and cool off and also "burped" the hoses as best I can
TB and IM have both been cleaned out. Are there any holes in specific I should check on the TB that may be causing this?
I have not adjusted the idle set on the TB, was hoping not to have to touch that until ruling out everything else.

I am looking at it this way. For the MOST part, the engine sits in the car right now as it would inside the engine bay of a 1998 Acura integra. There are 3 MINOR differences.
1) the IM was cut and 45* elbows were attached changing the runner angle
2) the intake pipe has been cut to about 1/4 the size it normally is
3) the header manifold has been shorted by about one inch on each runner

These are extremely small differences to blame a MAJOR problem on.
My problem is the car idles at aprox 1400 RPM. (normal should be 750 +/-50) With ever so slight throttle, it almost stalls out and revs up shortly afterward. after the throttle is released, the RPM's dip drastically to around 800 and shoot back up to 1400.