another injector install question

[erosedsm1]

I know there is a lot of these threads but searching didn't really answer my question. I installed a set of 750's in my car and ever since it will not idle smoothly at all. Initially it will just flutter around 1000rpms then after a few seconds fall to around 500 and periodically almost die. Giving it gas only makes the problem worse and the car is undrivable. I have also noticed the car does not pull nearly the same vacuum as it did with the stock injectors only around 11 lbs. I guess my question is, even though they appear to be installed correctly, could i be loosing vacuum where the injector meets the intake mani, and if so would this contribute to the crappy idle and vacuum? also what am i going to need to fix this problem? thanks

 

[oldman]

Don't tell me you installed the 750s without any fuel management, fill out your profile so we know what's going on.

 

[vault415]

Wow, that's what I was thinking. If you don't have an SAFC, DSMLink, or some sort of compensation for those beasts, 750's won't do much for you.

 

[Turbocharged]

Bigger injectors will make your car slower without fuel management. Not to mention the idle problems. You are running about very rich.

 

[SethA]

According to his profile he has a MAFT. Are all of the settings correct for the 750s?

Seth

 

[daren_p]

Well I don't know much about the maf-t setup but Im pretty sure you can compensate for injectors with that, which is listed in his profile. Unless he didn't adjust it to compensate for the new injectors?

Even if the injectors weren't compensated for, that still doesn't explain why he only has 11 "vac, are all you vacuum lines connected properly without any leaks?

Do you see or smell fuel anywhere to indicate a leaking injector?

Edit: Opps beat to it

 

[oldman]

Well, he must have just updated it, it wasn't there when I looked at it earlier. With that said, I still don't see a logger, not to mention the 750s are probably out of the maft adjustment range.

 

[sweet97]

The MAFT setting for 750's is AUX on "2" and BASE on "2".
Those inj's are out of the translators sweet range spot. You will get very high timing with it and 750's so I would set the base timing on 1* or 2*. Set the idle knob to where you get the highest vacuum reading. Start with the MID and WOT on "0" and adjust from there. Probably will have to lean them which will lead to noci iming ut puleddue to the knokWithout alogger itwilkl be a seat of thepants tune. Mark

 

[steve]

I guess my question is, even though they appear to be installed correctly, could i be loosing vacuum where the injector meets the intake mani?

What sort of injector insulators for the head did the injectors come with?

Steve

 

[erosedsm1]

sorry guys i haven't been on in awhile and for what ever reason my profile went to a default setting or something i didn't notice it until i posted the initial question and i forgot to mention that i also have a Jeff-o chip to compensate for the larger injectors. Even with that installed there was no change in the behavior of the car. there is no gas leaking anywhere and all the vacuum lines are connected, the only three lined not connected are the ones that go to the stock intake tube, the breather line, charcoal canister and the bcs have all been disconnected. I even swapped the 450s back to see if the injectors themselves where the problem, no luck the same spitting sputtering and fluttering and stalling. I also have a datalogger and it shows the ltft to be 5 and the o2 voltage to be .92 which to my understanding isn't too bad i know its not super accurate but still. Additionally, i have tried all sorts of things with the maft to try to smooth things out, no luck. as far as insulators go, none came with the injectors, just new o-rings, the factory insulators appeared in good shape so they were reused. As I understand it the insulators are the hard plastic pieces, the other questions on this topic get so confusing, it seems like people get the part names confused. i hope this clears things up sorry...

 

[kanderson111]

I cannot find in your profile what brand of 750 injectors you are using. Some brands of aftermarket injectors definitely will not work with the factory lower seals. I only have experience with the fic injectors and I know stock seals will not work on them, but if you tell us what kind you have I'm sure someone can help you out.

I believe Steve is talking about your lower seals, the hard pieces are spacers and I don't think they would be included with any injectors.

 

[erosedsm1]

well I'm not exactly sure they don't say anything on them, i bought them from a friend and he told me they were denso but any denso injectors i see from vendors are 720cc. one thing i do notice different about them compared to the stockers is the end that meets the head on the stock injector is squared off and on these it is more like a triangular point. i know that sounds vague but they only have about 1000miles on them and they have been cleaned and flow matched. they are black and that color, ill do some more searching to see if i can narrow it down thanks for the help guys I'm pretty sure this is my problem since the car was running fine before i changed out the injectors i just don't know what I'm going to need to fix it, am i correct in thinking that if not properly sealed this could create a vacuum leak, or possibly I'm just not idling at a high enough rpm to draw the proper vacuum, although that would not explain the extreme hesitation when i try to give it gas. thanks again

 

[snox135]

Well the hesitation sounds like your running rich and without knowing what size of injectors they are that's a good possibility. I would start doing some logs and playing with your maf-t settings to get it leaned out with out causing knock.

 

[truwarrior]

Did you take the spark plug wires off? If so did you get the fireing order right? I mixed up 3 with 4 and that made it run like crap.

 

[erosedsm1]

i do know the size of them but i just don't know the brandname. and yes i have checked the firing order too i just don't know if they are sealing properly the real question is, even though I'm not leaking fuel anywhere could a vacuum leak be caused by not properly sealing to the block. where can i get new and or different seals?

 

[sweet97]

The seals can leak. Get a new set from www.dsmotorsport.com maintanence section
I install my lower seals with high temp silicone and try to let them sit overnight before installing the injectors/rail. I have had them leak before with a leak test!
You most likely have a Delphi injector, barrel shaped, 2 colors. Often with GREEN o-RING ON TOP thatgoesinto the rail. I add a little grease to the o-ring that goes into the rail to prevent tears. Delphi's are usually black/green body. Maybeblack/grey. Mark b