H22 in 97 hatch running obd1. Starts without chip but won't start with chip
 

Ok so I'm trying to figure out what this could be.


I have a p75 converted to a p72 following the instructions on xenocron and pgmfi.org website. The chip job and vtec conversion is good, I've already tested all the traces and whatnot to verify nothing was burnt or damaged/broken.

So here is what the car is doing when I run a stock p72 crome basemap, or a p13 rom put on crome's 203 code.

I get no CEL. The car will crank and start but will die instantly and then just crank from that point on.

I tried using a stock p28 virgin ecu with the exact same results, as well as a stock p75 ecu. All three are acting the same.

Here is the kicker, if I pull the chip out of the ecu (or burn a bad rom, aka put it into limp mode) the car will start and drive around just fine but in limp mode.

So car starts and drives in limp mode, but won't start with a good ecu, even oem stock ecus and my chipped one.

SO anybody have any ideas what it could be? Maybe I'm just burning a bad rom?

Anybody have a verified good stock h22 crome bin?

Any ideas? I'm stuck right now .

It can't be mechanical as the car starts just fine with a bad rom in limp mode

Re: H22 in 97 hatch running obd1. Starts without chip but won't start with chip
 

i once had this problem and it was the chipping job on the ecu try a new one this is boosted93 off isr btw gl

Re: H22 in 97 hatch running obd1. Starts without chip but won't start with chip
 

I've tried quite a few ecus actually.

I tried a p13 that was actually bad at first. After finding out it was bad I switched to a stock p28, but that would act the exact same as my chipped ecu does when I have a chip installed.

Then I tried a p07, it acted the same. As well as a p75.

Re: H22 in 97 hatch running obd1. Starts without chip but won't start with chip
 

Ok I've been trying to think of ideas.


What exactly is the ECU doing when it goes into limp mode?
I'm thinking that perhaps it just doesn't refer to any sensors and runs on its own internal map.

If thats the case could it perhaps be a sensor that is causing a no start but when in limp mode it ignores the sensor?

What sensors could cause a no start?

I have all my sensors wired up to the correct pin locations however I'm wondering if perhaps the plug pins could be reversed on the engine side of the harness.

Things that have potential to be wired wrong are my IACV, TPS is plugged in right but probably needs adjustment, and the IAB pin wires at the engine side could be reversed as well.

Any sensors that will completely prevent an engine from running?

Re: H22 in 97 hatch running obd1. Starts without chip but won't start with chip
 

Nope. In limp mode the ecu goes to a smaller backup processor and limits rpms to prevent engine damage if it detects something wrong like a problem reading an external rom in a chipped ecu. It can also trigger limpmode if the car goes into boost on a stock ecu.
But it does read sensors

You just confirmed you have wiring issues when you said that.

It could be you have the wrong chip address setup in your burner.
************************************************** **************************************************
Chip addressing
Start at 008000 in hex end at 00FFFF

Buffering address
start in 000000
End in 007FFF

************************************************** ************************************************
You could have also forgot to remove the check sum.

I have a pretty good h22 rom. It's p30 code base though.

Re: H22 in 97 hatch running obd1. Starts without chip but won't start with chip
 

thank you for the help.

I've pulled the entire harness to figure out where the wiring mishaps might have happened.

I'll update if I figure anything out.

Re: H22 in 97 hatch running obd1. Starts without chip but won't start with chip
 

The ecu is working correct for sure now. I've tried it on two cars, both of which ran perfectly fine with it without any CEL. I'm also burning the rom with the correct addresses.

I triple checked my distributor wiring today and its good to go. I also checked my internal coil and its good.

I switched my IACV wires around and that actually helped out the idle but it's still only running in limp mode.


One thing I was wondering is because it was obd2a at first, I have a crank position sensor plug that is unused on my harness. Should I have done anything with that since I'm using obd1?

Re: H22 in 97 hatch running obd1. Starts without chip but won't start with chip
 

I dunno dude. I always have just used an obd1 engine harness. I think the crank sensor needs wired in with the obd1 distributor somehow.....I'm not sure though.

If the cars starting and running then it's got the crank and cam angle sensors working or it wouldn't fire at all.