2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

88 gxl won't run with 750cc injectors

Old Jan 17, 2017 | 09:25 AM
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88 gxl won't run with 750cc injectors

Hi I'm picking up my first rx7 on saturday and the guy I'm buying it from says it dies at an idle with 750cc injectors on it. He says it seems like it's dumping too much fuel. Do I need to go get it tuned to accommodate the extra fuel or what should I do? It has a 25mm turbo on it with some other supporting mods and I need to know what to do, please help! Thank you
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Old Jan 17, 2017 | 09:31 AM
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What ECU is being used as an unmolested turbo S4 would normally have smaller sized injectors.
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Old Jan 17, 2017 | 09:37 AM
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Originally Posted by satch
What ECU is being used as an unmolested turbo S4 would normally have smaller sized injectors.
he said it had a stock ecu, so yeah I think it's the s4
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Old Jan 17, 2017 | 09:38 AM
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What satch said, if it has the original ECU, it will never run right with those injectors, needs a standalone ECU to run them, or bare minimum a rtek 2.0
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Old Jan 17, 2017 | 09:43 AM
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Originally Posted by lduley
What satch said, if it has the original ECU, it will never run right with those injectors, needs a standalone ECU to run them, or bare minimum a rtek 2.0
Would the s5 ecu work? If not then I'll probably just buy some base injectors until I get enough for the rtek 2.0
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Old Jan 17, 2017 | 09:54 AM
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*bangs head on keyboard*


the ONLY stock ecu that has a chance of running it would be a turbo ECU, and you'd still need smaller injectors like the 550s and the turbo AFM and pressure sensor. not worth it because you need a standalone to actually tune the thing so your investment would have to be resold. but hey, this is what happens when idiots build cars and suckers buy them.

750s, probably upgraded pump, non turbo soft springy AFM, incorrect ECU mapping for a turbo, perfect scenario for dumping a ton of gas out the tailpipe and a flooded engine. i'd hate to even think what else is wrong with the setup on top of all that, because the sky is the limit there too.

what you need to do now is sit down and open about a hundred threads on diagnosing, building and tuning a rotary turbo engine and get a glimpse at what you bought and got yourself into. figure some things out and then come back if you still want to proceed with a little more knowledge.

contrary to popular belief, we aren't paid to help, so by condensing your questions it saves us a small bit of our lives.

Last edited by RotaryEvolution; Jan 17, 2017 at 10:05 AM.
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Old Jan 17, 2017 | 10:00 AM
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Originally Posted by RotaryEvolution
*bangs head on keyboard*


the ONLY stock ecu that has a chance of running it would be a turbo ECU, and you'd still need smaller injectors like the 550s and the turbo AFM and pressure sensor. not worth it because you need a standalone to actually tune the thing so your investment would have to be resold. but hey, this is what happens when idiots build cars and suckers buy them.

750s, probably upgraded pump, non turbo soft springy AFM, incorrect ECU mapping for a turbo, perfect scenario for dumping a ton of gas out the tailpipe and a flooded engine.
sorry this is my first actual project... Ill just buy the stock injectors and then save up, thanks for the advice
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Old Jan 17, 2017 | 10:19 AM
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An RTEK 2.0 could get it working, but it depends on what other dumb stuff was done to it. Standalone would be the ultimate solution.
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Old Jan 17, 2017 | 10:26 AM
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an Rtek 2.0 is still only a bandaid temporary solution, anyone running a turbo with half a brain wouldn't keep an Rtek in their car more than a year or 2.

it fills that shotty void for people who cant afford to do what they really need to do.
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Old Jan 17, 2017 | 10:39 AM
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[QUOTE=Noah Holmgren;12142430]sorry this is my first actual project... Ill just buy the stock injectors and then save up, thanks for the advice[?QUOTE]
Also the car doesn't run with the stock injectors...
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Old Jan 17, 2017 | 10:42 AM
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is the AFM hooked up, all the intake sealed 100%? getting spark? verfified you have fuel?

some additional details would be helpful

even if you get it running, it probably won't be drivable without a lot of swapping parts around, tinkering and purchases like a wideband to see what you're affecting. we're talking about specialized tinkering, like opening the AFM and tweaking spring rates which could potentially just destroy your AFM if you don't know what you're doing.
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Old Jan 17, 2017 | 10:43 AM
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Originally Posted by LargeOrangeFont
An RTEK 2.0 could get it working, but it depends on what other dumb stuff was done to it. Standalone would be the ultimate solution.
where could I get a standalone? Also the car doesn't run with stock injectors, could he have fucked up the ecu?
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Old Jan 17, 2017 | 10:46 AM
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this could make me cringe, but a few pictures of your engine bay and what you're working with might save a lot of back and forth here.
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Old Jan 17, 2017 | 10:53 AM
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Originally Posted by RotaryEvolution
this could make me cringe, but a few pictures of your engine bay and what you're working with might save a lot of back and forth here.
This is what he sent me
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Old Jan 17, 2017 | 11:05 AM
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everything appears to be in place, sort of. have you had the engine compression tested? because it wouldn't surprise me that it's blown with such a hokey rigged up setup...
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Old Jan 17, 2017 | 11:07 AM
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Originally Posted by RotaryEvolution
everything appears to be in place, sort of. have you had the engine compression tested? because it wouldn't surprise me that it's blown with such a hokey rigged up setup...
he said it ran perfectly before he removed the injectors. .. I haven't seen it in person yet, I'm going Saturday. Is it worth reading my 87 300zx for it?
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Old Jan 17, 2017 | 11:10 AM
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*facepaws*

does your car run? if so, probably not. you should also never take anyone you do not know's word for truth. these engines are very fragile and unforgiving to idiots and this car has already been turned into a grenade with the pin pulled out of it.

first thing to always consider is why someone wants to unload a car, is it because they can't figure it out? or is it because they are unloading a turd that they blew up and are lying? even in the best case here, someone spent all the time putting the turbo on and couldn't get the car running, now you're going in blind and expect better results? perhaps, but i tend not to rely on luck.

Last edited by RotaryEvolution; Jan 17, 2017 at 11:14 AM.
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Old Jan 17, 2017 | 11:13 AM
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Originally Posted by RotaryEvolution
*facepaws*

does your car run? if so, probably not. you should also never take anyone you do not know's word for truth. these engines are very fragile and unforgiving to idiots and this car has already been turned into a grenade with the pin pulled out of it.
mine does... I told him I want to get this one running before I traded... I found someone in my area with a t2 ecu and 550, 750 and 1000cc injectors. I'm thinking it might run with the 550s and t2?
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Old Jan 17, 2017 | 11:16 AM
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i tell ya what, forget about this car.

if you want a turbo rotary, sell your car and buy a turbo II. these converted cars are almost always pieces of ****. you're also still going to be lacking the turbo drivetrain, and i haven't even seen if its a 4 lug or 5 lug yet..


what you'll probably wind up doing is wasting a bunch of time and some money only to find out the guy was lying the whole time and blew it up.

and sorry, i know i can be a bit like sandpaper to people sometimes. i just give it how i see it.

Last edited by RotaryEvolution; Jan 17, 2017 at 11:19 AM.
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Old Jan 17, 2017 | 11:19 AM
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Originally Posted by RotaryEvolution
i tell ya what, forget about this car.

if you want a turbo rotary, sell your car and buy a turbo II. these converted cars are almost always pieces of ****. you're also still going to be lacking the turbo drivetrain, and i haven't even seen if its a 4 lug or 5 lug yet..


what you'll probably wind up doing is wasting a bunch of time and finding out the guy was lying the whole time and blew it up.
thank you, that's what I needed to hear... it's also a 5 lug. I was thinking of getting a frame and buying a motor separate to rebuild it, smart idea or no?
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Old Jan 17, 2017 | 11:22 AM
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piecing a car together can be hit or miss, usually miss, unless you have a lot of spare time to wait for the right deals or are very lucky. ideally just start with a complete car, if you really want to rebuild the engine from the start then something like this might work for you, however it is still a can of worms that needs to be sorted. buying a complete project n/a or turbo II is ideal, because you will have everything you need, except perhaps a few damaged internal engine parts.

you should start by compression testing the engine on this one, if you are still looking at it.
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Old Jan 17, 2017 | 11:24 AM
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Originally Posted by RotaryEvolution
piecing a car together can be hit or miss, usually miss, unless you have a lot of spare time to wait for the right deals or are very lucky. ideally just start with a complete car, if you really want to rebuild the engine from the start then something like this might work for you, however it is still a can of worms that needs to be sorted. buying a complete project n/a or turbo II is ideal, because you will have everything you need, except perhaps a few damaged internal engine parts.

you should start by compression testing the engine on this one, if you are still looking at it.
thank you so much for all the advice... I'll just keep saving and when I have enough I'll sell the z and buy a t2 if this one seems like junk
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Old Jan 17, 2017 | 11:39 AM
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[quote=Noah Holmgren]
Originally Posted by Noah Holmgren
sorry this is my first actual project... Ill just buy the stock injectors and then save up, thanks for the advice[?QUOTE]
Also the car doesn't run with the stock injectors...
If it won't run with stock injectors either, in all honesty walk away unless your prepared to put over a grand plus in it to get it running proper
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Old Jan 17, 2017 | 12:19 PM
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[QUOTE=Noah Holmgren;12142443]
Originally Posted by Noah Holmgren
sorry this is my first actual project... Ill just buy the stock injectors and then save up, thanks for the advice[?QUOTE]
Also the car doesn't run with the stock injectors...
What specifically does this mean?
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Old Jan 17, 2017 | 12:27 PM
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If the Z is your daily driver, don't sell it. This RX7 (or any project car) is not fit to be a daily driven vehicle.

Wait till you tell your Boss you cant make it into work because your 'new' car doesn't run. Now you will need another car and another job.
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