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GTA TECH Want to discuss technical topics about your GTA.... engine tuning, mechanical upgrades, problem areas, etc.? Then post it HERE!

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Old 07-12-2013   #1
Big&Bad89GTA
Car info: 1989 GTA 5.7L ASC Convertible, with RPOs: B2L, JG1, L98, and N10
 
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Have you checked your injectors lately?

Car running sluggish? Feels like a misfire? Long cranking, tough start? Dies when warm, won't re-start?


Check your injectors!!

Really easy to do...

Take a digital ohm meter, place across each injector leads and measure resistance...

13-15 ohms, that's ok...
10-13 ohms, may be on the way out...
9 or less, you are in trouble...

I had one @ 15, two or three at 12, a few at 4 or 5, and a couple around 2...

Replaced them all with an ethanol (that's the culprit to their demise) safe injectors and all is well...
I hope this helps - so basic, and the original Multec Injectors w/ exposed coil windings inside are bound to fail
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Old 08-25-2013   #2
metalman66
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GTA Year: 1988
GTA Engine: 350 TPI Automatic
Re: Have you checked your injectors lately?

Just did this to my 1990 TURBO GRAND PRIX. Made huge difference!!! the TGP guys end up putting ford yellow tops in as a replacement. BYE BYE multecs!!!What do you guys run with a stock setup.
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Old 08-26-2013   #3
86TA355SR
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Re: Have you checked your injectors lately?

I bought mine from SouthBay Fuel Injection. Great price and excellent service. They work great also.

They are the later style and are different from the OE injectors. Need to follow directions or you may have problems getting them to seal.

When I bought these, it was cheaper to buy from SouthBay than have the OE injectors cleaned...
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Old 08-26-2013   #4
merc3065
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Re: Have you checked your injectors lately?

I run accel 24# injectors.
I figured when I had the entire top of the motor off, I decided that I would change out that as well as the fuel pressure regulator.

I'm running around 48psi.
I also have a modified chip to handle the increased flow rate.
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Old 08-26-2013   #5
Big&Bad89GTA
Car info: 1989 GTA 5.7L ASC Convertible, with RPOs: B2L, JG1, L98, and N10
 
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Re: Have you checked your injectors lately?

Quote:
Originally Posted by 86TA355SR View Post
I bought mine from SouthBay Fuel Injection. Great price and excellent service. They work great also.

They are the later style and are different from the OE injectors. Need to follow directions or you may have problems getting them to seal.

When I bought these, it was cheaper to buy from SouthBay than have the OE injectors cleaned...
The Delphi Injectors were a drop-in, no drama swap. No issues to seal...

Injectors should read @ 16 ohms, or you are having troubles
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Old 08-27-2013   #6
GTABill
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Re: Have you checked your injectors lately?

Quote:
Originally Posted by metalman66 View Post
Just did this to my 1990 TURBO GRAND PRIX. Made huge difference!!! the TGP guys end up putting ford yellow tops in as a replacement. BYE BYE multecs!!!What do you guys run with a stock setup.
My son and daughter both have 90 TGPs. My son's is modded up pretty good but he's getting ready to switch his injectors and may be going with LS1 injectors to accomodate the bigger turbo and other motor mods. My daughter's is under construction, but her's will get upgraded stock style even though the previous owner supposedly replaced them.

As for the GTA, the multecs went bye bye back in 2010 and have never looked back. I went with the Bosch setup and same size on mine and love them.
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Old 08-27-2013   #7
metalman66
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GTA Year: 1988
GTA Engine: 350 TPI Automatic
Re: Have you checked your injectors lately?

Any part numbers for stock replacements.
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Old 08-28-2013   #8
GTABill
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Re: Have you checked your injectors lately?

Quote:
Originally Posted by metalman66 View Post
Any part numbers for stock replacements.
This is what I've got in mine and had no issues at all. Quick delivery and good customer service. Yes they are rebuilt, but their warranty is better than other brands new ones.

http://fuelinjectorconnection.com/sh...?productid=194
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Old 11-01-2013   #9
89JerseyGTA
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Re: Have you checked your injectors lately?

I just ordered a set of Bosch III's reman'd for my 305 Camaro 19 LB.

3 of the 8 injectors OHM'd bad. 5 were at .15, one at .13, .09 and the worst was .004, yes that is a .004. So basically that one is dead.

Just had it tuned and up Distrib, plugs/wires, runs better but still chugs at low rpms so that bad injector must be the culprit.

Any advice for a green horn - never installed injectors before, saw vid on YT, looks easy, but what to beware of - advice is appreciated.
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78 Trans Am(84 to 86)
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Old 11-01-2013   #10
90 L98 TransAm
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Re: Have you checked your injectors lately?

I also recently ordered some Bosch IIIs to replace my factory originals. They are the blue Ford ones rated at 24 or 27 lbs./hr. (depending on the test fluid and pressure).

three of my injectors had low resistance. not sure if they are the cause of my rough hot idle (replacing the IACV and cleaning the passages didn't do much) but figured I could use an upgrade for my supercharger.

bought a hand vacuum pump to test the EGR valve and solenoid and will be installing a TPIS fuel pressure regulator while i'm in there. but I probably won't do this job until Spring.

so if anyone does this in the near future take some pics and make a thread!
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Old 11-03-2013   #11
89JerseyGTA
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Re: Have you checked your injectors lately?

Hey we should compare some notes - I got a fuel reg also, along with new tpi/runner gaskets. My plan is to not have to take the plenum off again as I just did the egr valve about 3 months ago.

Only other thing under there I didn't replace yet was the IAT intake air temp .. only $15, might as well I guess. I just did the GTA egr also, should have done the IAT there .

I tried to tap on the bad inject with a screw driver see if it would come bad to life - no luck. Listened to it thru the screw driver and it is clicking just like the others, but still read .004 on the resistance.

I was reading that the Bosch III's needs an adaptor on South Bays website to make up for stock injector length then it says it doesn't need ....confused a bit. I didn't buy from SB ... but wonder if they will fit ?

Anybody ?

The Bosch Design lll fuel injectors are .125 to .25 inch shorter than the stock TPi injectors. To solve all fitment issues we designed an adapter that fits onto the bottom of the injector. They are now the same length o-ring to o-ring as the stock TPi injectors. No modifying or milling necessary. Just "Plug n Play". INSTALL INJECTORS INTO INTAKE MANIFOLD FIRST, THEN THE FUEL RAIL FOR PROPER INSTALLATION & FITMENT !!!!!! These adapters are exclusive to SouthBay Fuel Injectors. 516.442.4707
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1990 Iroc Vert 305
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78 Trans Am(84 to 86)
84 Trans Am (86 to 88)

Last edited by 89JerseyGTA; 11-03-2013 at 06:13 PM.
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Old 11-03-2013   #12
90 L98 TransAm
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Re: Have you checked your injectors lately?

Quote:
Originally Posted by 89JerseyGTA View Post
......I was reading that the Bosch III's needs an adaptor on South Bays website to make up for stock injector length then it says it doesn't need ....confused a bit. I didn't buy from SB ... but wonder if they will fit ?

Anybody ?

The Bosch Design lll fuel injectors are .125 to .25 inch shorter than the stock TPi injectors. To solve all fitment issues we designed an adapter that fits onto the bottom of the injector. They are now the same length o-ring to o-ring as the stock TPi injectors. No modifying or milling necessary. Just "Plug n Play". INSTALL INJECTORS INTO INTAKE MANIFOLD FIRST, THEN THE FUEL RAIL FOR PROPER INSTALLATION & FITMENT !!!!!! These adapters are exclusive to SouthBay Fuel Injectors. 516.442.4707
I did buy these from SouthBay. they are 2.95" from end to end and the instructions that came with them indicates they do include adapters and do not require clips. I planned to carefully compare the new and factory injectors when I removed the originals.

maybe someone can measure the length of one of their factory Multec injectors.
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Old 11-03-2013   #13
89JerseyGTA
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Re: Have you checked your injectors lately?

This is the pic of the actual injectors I'll be getting.

I have the contact info from the seller, have to ask the question about if they have adapters, looks like a "no clip".

FuelReg, comes as a set w/ O rings.
Attached Images
File Type: jpg 140.jpg (4.6 KB, 19 views)
File Type: jpg $(KGrHqF,!nkE-vr0fBZ8BPzEVec-Nw~~60_12.JPG (25.5 KB, 20 views)
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89 GTA 350
1990 Iroc Vert 305
Previous cars
69 Camaro (81 to 84)
78 Trans Am(84 to 86)
84 Trans Am (86 to 88)

Last edited by 89JerseyGTA; 11-03-2013 at 07:49 PM.
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Old 11-04-2013   #14
GTABill
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Re: Have you checked your injectors lately?

The Bosch III injectors I got from the link I posted were the same size as the Multecs, so I didn't have to have any adapters..........plug em in and I was off and running. That was 3 years ago and no issues.
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1991 Bright Red GTA...1st place Light Modified Class 2009 & 2014 TA Nationals
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Old 11-04-2013   #15
djmarch
1989 Gunmetal Grey, 350 TPI, 700R4, 3:27 BW
 
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GTA Year: 1989
GTA Engine: 350 TPI Automatic
Re: Have you checked your injectors lately?

Keep in mind if you are running SLPs' siamese intake runners, you might run into an interference problems.
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Old 11-04-2013   #16
89JerseyGTA
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Re: Have you checked your injectors lately?

Thanks Bill,
Good to know they fit well and they job was painless.

Did you do a fuel reg also ? Just hope my plumbing skills hinder my results, compression fittings, orings 0 hoping for the best !
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1990 Iroc Vert 305
Previous cars
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78 Trans Am(84 to 86)
84 Trans Am (86 to 88)
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Old 11-05-2013   #17
GTABill
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Re: Have you checked your injectors lately?

Quote:
Originally Posted by 89JerseyGTA View Post
Thanks Bill,
Good to know they fit well and they job was painless.

Did you do a fuel reg also ? Just hope my plumbing skills hinder my results, compression fittings, orings 0 hoping for the best !
No, I still have the stock fuel pressure regulator. Looking back, I kinda wish I would have gone adjustable, but since I show it at the TA Nationals, I'm limited to mods and that would probably push me into the next category. Plus I'm really trying to keep everything as stock as possible when it comes to the car as a whole with the injectors being the exception since they were famous for being junk.

The hardest part I had was getting the fuel lines hooked back up and thats because I took as little off as I could to get the job done........I have a tendency to lose bolts lol, but I'm sure you will be able to get it done.
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1991 Bright Red GTA...1st place Light Modified Class 2009 & 2014 TA Nationals
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Old 05-07-2014   #18
90 L98 TransAm
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Re: Have you checked your injectors lately?

Quote:
Originally Posted by 89JerseyGTA View Post
This is the pic of the actual injectors I'll be getting.

I have the contact info from the seller, have to ask the question about if they have adapters, looks like a "no clip".

FuelReg, comes as a set w/ O rings.
Jersey - i compared the length of the injectors i bought from South Bay to the factory injectors. best i can tell they are within 1mm of being the same length. these are the blue 24/27 lb. Bosch IIIs. i can post a comparison picture later.

concerning the O-rings that came with your regulator - where do the largest and smallest o-rings go? i only found a place for the other seven.

thanks
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Old 05-08-2014   #19
90 L98 TransAm
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Re: Have you checked your injectors lately?

Here are the two injectors:

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Old 05-25-2014   #20
MunsonGTA
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GTA Year: 1987
GTA Engine: Custom
Re: Have you checked your injectors lately?

I checked mine the other day just for the heck of it. 2 at 14.6, 2 at 14.7, 4 at 14.8
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11.16 at 123 mph.
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