I have an odd issue that only a handful are facing, none got it resolved.. i'm suspecting it could be the haltech..

so, straight to the point, what's gonna happen if i remove the connection from the haltech and fix it back on the stock ECU to manage?

vortech sc, walbro fuel pump, dw 600 injectors, RFS stage 0, cams, pistons.. i think those are the important parts u may consider.

any ideas?

thnx

 

stock ecu is setup for stock injectors. With the larger injectors you will run very rich and probably foul the plugs. Since the injectors are just over double the size you will be getting double the fuel on a stock map.

 

it will run perfectly fine and correct AFR unless you tip into the gas too hard. It will start just fine, idle at stoich, etc. ran mine like that all time, with and without my cog belt installed.

 

but isn't the stock ecu already set up to run stock injectors with pre-valued injection pulse/width? i.e. the ecu will be telling the injectors to run/spray this much fuel, no matter how big the injectors are?

hope that makes sense.

i'm just thinking out loud

 

what about the different compression ratio? cam timing?

any idea if those have a direct effect?

 

The stock computer is of course setup for stock injectors and no return fuel system. That being said, it has o2 inputs that it will trim fuel +/- 25% based on. If you just need to start up the car without Haltech, you should be ok to do so. I would not advise boosting on the stock computer or driving for extended time without a proper ems (Haltech) or Uprev dyno tune for your modifications or permanent damage could be caused.

 

It sends a set injector pulse width. So if that pulse width is say 1.5 miliseconds then the injector will open for that much time. If you have a larger injector the ecu will still send the 1.5 ms pulse so the larger injector will be open the same amount of time as the smaller injector but now it lets considerably more fuel in during that same time frame.

As long as you are within the 25% fuel corrections then it should be ok. I know I had to reduce my IPW (at idle and cruise) quite a bit going from stock injectors to the dw600's when I was supercharged.

It's not going to ruin an engine if it's rich but it will waste fuel and could foul some plugs.

 

i'm gonna do that soon and post back the results. i might have to drive the car for a while on the stock ecu, no boosting, no hard driving, i just need it to take me from point A to point B below 60mph...


thanks for the input guys.

 

How long is "a while"? Just to a shop or around town? If it's around town I would just swap a set of oem injectors in. I just had my injectors out and it took me around an hour to pull them out, check them over and re-install them so you won't be out much time.

 

i drove for maybe 700 miles like that to different tuners until I realized how simple the UTEC was to use.

 

a "while" is basically taking the car to a garage to get things diag'ed and probably part out.. i might end up selling the car soon because of the uknown/unresolved issue.

where can i find instructions on how to open the passenger-side dash to reach the ecu? thnx

 

Reach under the dash, pull down black cover, ecu is held in place by 2 bolts I believe. It's really easy to get to.

 

nothing is coming off.. i'm afraid i could break something.

 

hmm, I'm not sure. I've never had a problem removing panels. Check the FSM for the exact procedure

 

sorry to hear that u will part out your car, i saw your car once or twice in the road, i really like your car its so unique. in Bahrain we really dont have a good tuners for VQ engines. please tell me which parts you want to part out.. i might be interesting.

i'll pm you

 

Thanks bro..

sad, but true.. it's not much to do with the tuning really.. it is probably something to do with car electrics, but no one can point it out.. and now i don't have time to go back and forth to try and fix that issue, which could be really silly and simple to fix..

i'll put the car back to stock, i'll even sell or trade the engine and then sell the car in a stock form.

 

Since you have an RFS you can lower the BFS to something low like in the 30's that should at least keep from fouling things up with the bigger injectors.

 

gotta remember at lower fuel pressures, injectors dont atomize well and will compound the issues.

Like I said, I ran my car or hundreds of miles on untuned stock ecu and 600cc injectors with no issue.