Mitsubishi 3000GT & Dodge Stealth Forum banner

1 - 13 of 13 Posts

·
The dark shall be with us
Joined
·
7,350 Posts
Discussion Starter #1 (Edited)
Well I never thought to be one of the people asking internet for help but here I am. Lol I changed my injectors to 800cc because I was running out of fuel on e85 and dr650s. I first bought a wrong set and were high impedance fuel injectors since I thought all fat body injectors are low impedance. When I put those on the car was missing and was running lean. I thought there is a vacuum leak somewhere but couldn't find it. Later I found out I got the wrong injectors. So I bought the right 800cc injectors and the car still running lean and missing. Is it possible I'm running safc or could it be something else? I know for sure I didn't drop anything down the intake to bend valves but I'll do compression test tomorrow. I have not driven the car for 5 weeks. I'm super pissed. I thought maybe safc at least would make it run rich but running lean and missing is confusing me. When I was running 650cc injectors I was at -15% on e85 and -20 on gas when idling so I thought I would have plenty of room for 800cc. What are your thoughts? Bad fried ECU? Smaller injectors (would suck since max I could run was 20psi at 113% duty cycle on 650s)? I also noticed my fuel pressure doesn't hold when I shut off the car but I have 40 psi when idling.

Sent from my SM-G955U using Tapatalk
 

·
Registered
Joined
·
5,838 Posts
What injectors did you buy? Have you tried anything other than idle? Bigger injectors have more dead time and act way smaller than they are with an safc at idle.
 

·
Registered
1993 3000GT VR4
Joined
·
2,125 Posts
5 weeks is not enough time for the fuel to be a problem. I have let cars sit for 6 months without the fuel in the tank becoming a problem.
 

·
Premium Member
Joined
·
6,958 Posts
Pretty confused by your post...? What were your SAFC settings with the 650's? What are they now? If it's lean, give it more fuel...

Are you sure it's even lean? If you fouled a plug or otherwise caused a misfire, your wideband will only see the O2 in the unburned mixture, and erroneously show lean...
 

·
The dark shall be with us
Joined
·
7,350 Posts
Discussion Starter #6
Pretty confused by your post...? What were your SAFC settings with the 650's? What are they now? If it's lean, give it more fuel...

Are you sure it's even lean? If you fouled a plug or otherwise caused a misfire, your wideband will only see the O2 in the unburned mixture, and erroneously show lean...
My wideband shows lean. Like so lean to a point that it won't even show the numbers anymore and says lean. On ethanol I was around -8 with 650s. I even gave it more than that and it gets a little bit richer and then goes lean again. I have e90 in the tank if that would make a difference. Maybe I should put MAF-T and see how that works. Is it possible it's the ecu that is pulling fuel?
Plugs are brand new.

Sent from my SM-G955U using Tapatalk
 

·
Resident Street Racer
Joined
·
5,605 Posts
throw your old injectors back in and start from a clean base. If everything returns to normal, send your 800cc injectors out for clean and flow service.

agreed 5 weeks sitting is nothing.
 

·
The dark shall be with us
Joined
·
7,350 Posts
Discussion Starter #10
It's pretty hard to see which is missing since I don't see much of drop in rpm when I pull the plugs but it seems like it's the 6th one. Same as when I had the wrong injectors. I'll test and see if I got the right injectors this time and put a MAF-T in while I'm at it.

Sent from my SM-G955U using Tapatalk
 

·
Premium Member
Joined
·
6,958 Posts
My point was pretty simple... If it's misfiring, ignore the damn wideband... It's lying to you.

What are your fuel trims at idle? Do you have one bank showing really lean and the other normal or rich? The lean bank will be the one with the misfire.
 

·
The dark shall be with us
Joined
·
7,350 Posts
Discussion Starter #12
Well I let the car idle for a while and the missing went away. I used a Data logger to shut off injectors one at a time and cylinder 5 made no difference in rpm or afr. I connected a 9 v battery to it and after a few min it got fixed. Now I'm having a hard time tuning it. It goes from rich to lean to rich under boost. Drives just fine though so I guess MAF-T is a must.

Sent from my SM-G955U using Tapatalk
 

·
The dark shall be with us
Joined
·
7,350 Posts
Discussion Starter #13 (Edited)
Well, I got the car together and I'm still having some issue. I don't know maybe my aftermarket afr reads wrong but my injector duty cycle is still too high for the boost I'm running. I had many breaking up issues but it was somehow fixed when I leaned it on MAF-T. Now at 19 Psi dropping to 18-17 and I'm already at 95% duty cycle with 800cc injectors and a 450 fuel pump with boost a pump. The pump on its own should support 550whp with e85 and calculation online says about 600hp with 60 psi fuel pressure for the injectors so why on earth my duty cycle is so high? I guess I should get the car on the Dyno to get the correct afr. How much power should I be making with the old style dr650s around that boost? I was looking to make around 450whp but I know no way I'm making that much with just 20psi.


Here is another thing that got to my mind. If pulling fuel with safc adds timing then does it mean we can control timing of we make it super rich on MAF-T and then pull fuel on safc to make it even while add timing or do they cancel each other? Or make it lean on MAF-T and add fuel with safc to pull timing?

Sent from my SM-G955U using Tapatalk
 
1 - 13 of 13 Posts
Top