I have a bad P28 w/S300. I thought it was a wiring problem until I put it in another car and the same problem existed, fuel pump not coming on. So to test to see if it is the ECU, can I use a PR4? Its the only ECU I can borrow for the time being. Will the car be able to be street driven?

Also, how can I test to see if its really the ECU and not the S300? Also I may have a micro-solder tech look at the "bad" P28 to see if there are any visible circuit board damage. Are there any diagrams for him to use as far as circuit board repairs, like a schematic?
Thanks!

Car: 1988 CRX
Eng: 95 H22A

 

The car will "run" on the pr4 but I do not recommend driving on it much.

There are no public "diy" ecu repair schematics available.

 

Ok. It's what I drive to work so that's why I was asking. I was hoping I could drive it say 5 miles one way until I get ahold of a new P28 w/S300.
I don't want to play "20 questions" but what harm will that ecu do to the engine?

 

Most likely it won't do any harm for a 5 mile drive etc.

 

Ok cool. Just no track time. lol

 

Sorry I was mistaken. It's a PR3.

 

check ur ecu for bad solder joints...

my friend has a chipped obd1 pr3 that he got from a shop, and it worked fine for years, hes had the ecu for about 5 years now, but he hasnt used it for the last year or 2 since we took his motor out and put the stock one back in...

we swapped his motor again and went to use the pr3 and its doing the same thing, to where the fuel pump wont prime and the cel stays solid, if i flicker the key from acc to run a few times sometimes the cel would turn off the fuel pump would prime and it would run for about 30 seconds then die out and cel again...

i looked at the board and it has alot of dry solder joints mostly around the injector drivers and that area of the circuit board...

i havent had much time but im going to desolder alot of the board, mostly where i see problems and re solder it see if it works then i was just thinking about that since it worked before but now it doesnt out of nowhere..

 

I also read that the capacitor on C14 on the circuit board goes out. That runs the fuel pump circuit. So I ordered one of those for $2. I'm going to be speechless if that fixes it.

 

i never thought of that, im going to replace that when i get off work and see if it works i have a spare one lol that i never put in when i got my chipping kit for another ecu lol

 

Let me know if that works and how you did it. I've never soldered anythng before and I'm goin to have a friend do it. He works on circuit boards. Plus, mine won't be in until Thursday or Friday.
Hope this solves our problems.

 

I have posted a couple how to fixes for this very situation.

More than likely it is the C14 capacitor.. but be ready to do some other repairs/jumpers as that capacitor usually takes out some of the traces around that area.

 

First thing you should have done was bypassed the J1 jumper to check the stock side, cut your troubleshooting in half.
If you have a voltmeter, just measure across C14. It's a good idea to replace it anyway, but if that's not the problem you wasted 3 days waiting for it in the mail.
The PR3 tables are significantly different, if you have to use it just drive like a vagina. If it hiccups and surges, you're doing good 'cause it hasn't blown up yet.

 

well the pr3 my friend had was chipped and not working, so i took my desoldering iron and desoldered all the solder joints took the socket and 74hc373 out and chipped a p28... i havent tested the pr3 yet since i have replaced c14 to see if it works...

if you have the right tools desoldering and soldering is a piece of cake

 

So i replaced the capacitor on C14 with a new one and it still didnt work.
It started because of the leftover fuel in the engine from the PR3 but, as soon as I touched the pedal it died - fuel pump still not coming on.
I think my next option will be to get another socketed P28 from HAmotorsports and just plug my S300 into and roll. I was just hoping to avoid spending $150.