Help With New Engine

[Finny]

Hi all, Just finished getting my freshly build RB30DET in my R33. It has 550cc RX7 injectors. problem is, to get it to run at all I have to set my SAFC II to +50%..... shouldn't that be running RICH AS HELL!!

I calculated that I need -33% to get stock fuel ratios so why wont it idle with out +50%.

I was thinking that maybe I have wired the injectors up wrong, I made my own plugs up temp until I can get a hold of some proper injector plugs. So at the moment the injector power it closest to the back of the car and injector signal is towards the front of the car. This is how the stock RB25DET has it, are RX7 injectors the same. I checked the impedence on the injectors and they are high impedence like the RB25DET ones.

Also for some bezzar reason I had no voltage on my gray injector power wire.... I just hocked it up to ignition but why would that have happend?

Edited February 10, 2008 by Finny

[The Mafia]

so you're only running the factory ECU?

You should have upgraded the ECU to run bigger injectors

[Finny]

Factory ECU is fine to get the car running so I can get it to dyno. My mates 13 second RB30DE (non turbo) runs stock ecu with obviously larger injectors.

Thing is, if I need to run 150% petrol just to get it to run then there is something seriously wrong. I am running larger injectors and richening it 50%.... so there for it should be running like 7:1 AFR and it shouldn't be igniting.

[rob82]

Pretty sure you have selected the worst injector for the application.

[Finny]

Injectors came with the engine.

[rob82]

Injectors came with the engine.

If your looking to run the engine in - depending upon the fuel rail setup put the standard injectors back in until your happy that the engine is run in. THe look at doing bigger injectors and ecu afterwards.

[Finny]

the rail is top feed... you still make no sence. I will go and get the car dyno tuned but there is no point me dyno tune it if there is somefin f**ked with it. I dont care about swapping injectors or ECU or anything because I know I can get the car running nicely with thoes injectors and a SAFC... I have seen it done before. I just want to know why I have to run double petrol in it, then bigger injectors and its still too lean. It makes no sence. Its like sticking 1000CC injectors in an R33 and then have it running too lean with stock ecu. The car should be too rich to start.

Edited February 11, 2008 by Finny

[James_03]

Sounds like the wiring is incorrect somewhere. You should have 12v live on the gray wire with the ignition on, but that makes no sense that you don't because if that was true the injectors would not be firing at all. The ECU pulses ground signals to each injector to fire them, so chuck a multimeter on the grey wire with your 12v, then the other wire to negative. Take out the CAS and spin it and check that it pulses for each plug. Otherwise rig up a 12v check light.

I don't need to reiterate how shit rx7 injectors are as its already been done, I can only hope you had them cleaned/flow tested prior. I bought 6 a while back and ended up with only 2 that had an acceptable spray pattern. That after I got them to work at all.

Also go over your calculations again and make sure your taking the right amount of fuel out. Whats the denso part number on the injectors? What size?

Let us know how you go with the above anyway.

Edited February 11, 2008 by James_03

[Finny]

Trust some one from the R31 club to make a meaningful post. Yeah I couldn't get the car to start at all. multimeter on the gray wire and nothing. A friend of mine had to hock up a 12v wire to his gray injector wire when he put an RB30DE in his R31 so he said maybe you have to do the same?? doesn't really make any sense. There is no fuse or any thing that governs the injectors?

Ok here are my calculations. 550cc injectors -33% = 368.5cc so if I run -33% on my SAFC is should run stock AFR. But... at -33% it wont start at all. at 0% it will start but hates me. at +50% it starts and I can drive it but it misses a bit and carries on. so +50% on a 550cc injector is 825cc... how the hell is it running at that. obviously it isn't actually getting that much fuel that is what I am trying to sort out. I might take it to an auto electrician.

[rob82]

Trust some one from the R31 club to make a meaningful post. Yeah I couldn't get the car to start at all. multimeter on the gray wire and nothing. A friend of mine had to hock up a 12v wire to his gray injector wire when he put an RB30DE in his R31 so he said maybe you have to do the same?? doesn't really make any sense. There is no fuse or any thing that governs the injectors?

Ok here are my calculations. 550cc injectors -33% = 368.5cc so if I run -33% on my SAFC is should run stock AFR. But... at -33% it wont start at all. at 0% it will start but hates me. at +50% it starts and I can drive it but it misses a bit and carries on. so +50% on a 550cc injector is 825cc... how the hell is it running at that. obviously it isn't actually getting that much fuel that is what I am trying to sort out. I might take it to an auto electrician.

Just because you remove 33% of the maf value doesn't mean you will get 33% less fuel. Your probly sitting on the minimum injector on time. This still doesn't explain why the fueling is lean. Are you sure its lean and not a rich missfire? What do the plugs look like? Try holding the engine at 3000rpm and then adujust the SAFC. Did you have the injectors cleaned and are they all pulsing? Apply battery voltage to both the terminals of the injector and make sure they click when powered. You will still struggle to get the idle mixtures correct though with the shite spray, I mean squirt pattern those injectors have.

[Finny]

true, my cams also make idle nice and lumpy

I understand what you say with minimum injector time but it wont idle on stock AFR even though you would think the RX7s would put out more petrol than the stock ones. thing is when I run +50% on the SAFC it idles much better.

I am at work so its hard to tell until I get home but I think it may have a bad earth meaning the injectors aren't opening fully or something like that. They are all pulsing, not getting any black carbon smoke out the back so I doubt its running rich.

I will get after market management later on, its just that I wasn't planning to have my engine blow up and then spend BIG $s on my new one... so I am kinda broke for a bit.

[shanef]

park it in the shed until you have the money to buy the correct parts to do the job properly

you shouldnt be f**king around with the std ecu + afc + shithouse injectors on a built motor

no wonder ur having problems