I ordered Southbay Fuel injectors for my 86 TPI Trans Am 5.0L. I changed out my injectors a couple days ago, and I cannot get the car to run right. It's backfiring through the intake, loading up, and will not idle. My new plugs are soaked in gas. It ran fine before I did the change, I just wanted to upgrade to the new style based on what I read on the board. I took my intake back off today and sealed/checked it to be sure it's not a vacuum leak. I've researched all over the boards, and web trying not to have to post this question, but I'm pulling my hair out.

Car only has 47,000 miles. It has new cap/rotor/coil, ignition module, wires, fuel pump/filter, and I have pretty gone over the whole car. New exhaust, cat, belts, hoses, tons of parts. I had been preparing to drive it to Texas from Ohio, since we are moving there. I'm doing all of my own work on the car.

Check engine code comes on and is 44 plus the usual 12. (I have a new O2 sensor on there, too) Fuel pressure is 38 at idle. Also, it has a new coolant temp sensor.

Also, no fuel in my regulator vacuum line...
Any ideas?

Thanks!

Tara

 

Hey Tara, please give us a call tomorrow and we will do whatever we can to help you.

 

Hey, thanks. I will do that.

 

Sounds more of liking a flooding issue. Did you re check the o rings on the injectors? Or it could be a bad injector or a few so the computer is sending more fuel then air causing it to flood out and die.

 

I didn't recheck the orings, I installed them into the manifold first then put the fuel rail over them. Used KY lubricant on the orings when I put the injectors in. I felt them go in good and tight, then I tightened down the 4 bolts that hold the rail on. The fuel regulator isn't very old, either. (stock replacement)

 

did you mix up your injector connectors? plug wires? is the vacuum line to the regulator hooked up? did you get the wrong injectors (too big)?

 

vacuum lines are all hooked up, I've checked that several times. Also triple checked the plug wires to be sure they are in the correct firing order as well. I don't think I messed up on the injector wires. I can check again tomorrow. I got on southbay's site, and my injectors look exactly like what I ordered on their site. (light tanish yellow color 19lb bosch III)
Thanks for the help so far, I've got to get this fixed. I walked away from it and didn't look at it all day yesterday hoping I'd have a fresh outlook today. Wasted a whole day working on it, and still the same thing.

 

By chance you didn't mix up the runner gaskets on the plenum, they are easy to mix up, causing a leak.

 

if you put bigger injectors in, it's gonna run rich until you get a new chip burnt for them.. if they are a little bigger than stock the computer might be able to compensate and keep the a/f ratio fairly close and you can get by, but if they are a big upgrade then you will need a new chip made for them.

did you hook the vacuum line back up to the fuel pressure regulator- no vacuum causes the pressure to go way up, which makes it run rich.

 

do you actually see them leaking??? Or is it just running pig rich?
Are all of the plugs wet?

www.southbayfuelinjectors.com
516-442-4707

 

How does it run when the engine is cold, in open loop mode? Is it really rich then too? Ohm check both temp sensors.

 

[quote=tarathatcher;5389035]I don't think I messed up on the injector wires. I can check again tomorrow.quote]

since your not sure, hopefully its as simple at that

a new vacuum hose to the FPR would not hurt either incase of cracks/pin hole, and its cheappp

 

Nothing leaking at all. Runs way way worse (if that's possible) when it's cold. Ohmed the injectors and they are all 16.6. All spark plugs are wet. Runner gaskets are all correct, no leaks from there. I'm walking away from the car today. Don't want to get too angry at it. I've worked on cars forever, rebuilt engines by myself. I don't doubt my mechanical skills, but man this is making me start to wonder!

 

Take the regulator vac reference hose off and see if there is any fuel in that. Could be the reg is going. The other thing that has not been mentioned is what size injectors did you replace the stock ones with? A chip would have to be burned to compensate if they are any different then stock.

 

They should be 19 lb injectors. I took off the vacuum hose to the regulator, no fuel in there. (Doesn't even smell like fuel) I could replace the regulator with a stock replacement anyway I suppose. Only thing that was changed was the injectors this time. All the other tuneup items I did before, and was driving it. It had a slight stumble, and when I had ohmed my old injectors, I found a bad one. That's why I ordered the new injectors.
Only other thing I did was I cleaned the EGR valve. Maybe it's stuck open?

 

Did you touch the distributor when you changed them? It sounds to me like it's a serious timing problem.

 

Can you verify your fuel pressure? I could see one leaky injector, but not all eight. And it must be all eight flooding the engine like that. When the engine is cold, the ECM sets the pulse width to the injectors based upon a table. As long as the injector is sized right and the fuel pressure is correct, then the amount of fuel will be correct. The most likely reason seems to be that the fuel pressure is too high. Once the engine warms and tries to go into closed loop, the ECM will try to fix things up by narrowing the pulse width to an extent.

 

Tara, afremont is correct, it would be highly unusual for all 8 injectors to be leaking.
We leak test all of our injectors up to 80psi.
Can you send them in? We will be more than happy to check them for you.

 

Tara, I am going to go out on a limb here but Since you have a cold start injector(I assume as your have an 86), is it possible that you plugged an injector pigtail onto the coldstart? That would cause a lot of fuel to enter the motor.

 

I have one of those on the rail gauges. I suppose it's a slight risk of a leak especially in an accident, but it's piece of mind to be able to see what's going on any time I want.

One way to check for leaking is to turn on the key and let the fuel pump prime the system. Wait a few seconds (like 10) and push on the schrader valve on the fuel rail to see if fuel squirts out. If the injectors are leaking badly, there will be no pressure 10 seconds after turning off the key. A well working system (regulator, fuel pump and injectors) will hold pressure for minutes after priming.

 

I can send the injectors in. I'll have to find your address. It's been a few months since I ordered them. I am just getting around to putting them in because I've been in San Antonio moving in. I'm back in Ohio trying to get things together for the final trip back to Texas.

I verified the cold start injector harness was correct as well. I have a Hypertech fuel gauge that I use on my old Chevy van and the Trans Am. It seems to work good so far. The car seems to hold pressure at least a few minutes after I turn the key off. I didn't touch the distributor or wires when I took it all apart. I should be pretty good at taking the plenum off, this will be the fourth time now.

what are the odds that my MAF decided to take a dive? It would be pretty coincidental.

Checked TPS voltage, and it's at .54.

 

Send them to:

SouthBay Fuel Injectors
566 Merrick Road
Suite 3
Rockville Centre, NY 11570

 

The fuel pressure should hold for hours after turning the car off and bleed down very very slow. My pressure will hold for days at 30 plus at the rail. If the pressure gauge bleeds down to zero in 10 minutes the injectors are leaking fuel.

 

Not long ago someone else here on TGO had this same exact problem. After replacing the injectors the engine ran like doo-doo (that's a highly technical term ).

The issue was the wiring to the injector connectors. The wires were basically falling apart inside the rubber boot where they enter the connector housing.

RBob.

 

Or the regulator is leaking or the fuelpump check valve is leaking.

A lot of cars bleed off PSI, an start and run just fine. mine is one of those.

 

Update: I reset the computer, and unplugged my MAF. Even on 8 fuel soaked spark plugs, it ran and idled!! Checked one new plug I put in, burning great! So, plugged in MAF and reset computer. Checked plug again, fuel soaked. Must be my MAF! How coincidental that it would go out when doing my injector swap. For anyone else in the future regarding this situation, I was not getting a MAF code. (at least until I ran it without the MAF during the test)

Now, need to order a MAF....and fix the rear axle brake line that started leaking while just sitting in the garage.

Thanks!!!!

 

Good to know that it's not the injectors and you only have to replace the MAF now! There are tons of used ones out there for cheaper than new.

 

I second that

www.southbayfuelinjectors.com
516-442-4707

 

nevermind

 

From your original post, it all started after you changed injectors, so, if it was me, i would stick to just a fuel problem, which of coarse is the fuel injectors, fuel regulator, fuel pressure, etc. Maybe replace the injectors with your old ones, just to see if anything changes? Like was said earlier, also check your wiring to the injectors.

 

Yep, changed back to the old injectors today to try it out. Runs the same. I'll check the wiring again.

 

As I mentioned in this thread on more than one occasion, send them in and we will
put them on the bench for you. You could have had them back by now.
Remember, the injectors sat on the shelf for quite some time. If one is stuck open
we can fix it and have them shipped out the same day.

 

Any updates?

 

It was a vacuum leak, I plugged off the cold start injector and fixed that issue. The cold start injector was bent slightly. I've been chasing a intermittent code 33 for months now It's still not driveable, it surges on the highway and flashes the check engine light intermittently. (has new MAF and relays, checked tps) i'm ready to throw in the towel. Even upgraded the Prom (89 without VATS), which BTW, made a massive difference in power when it runs right.

 

You recall which vacuum line it was?

 

It was the actual cold start injector mounted to the plenum that was bent. It wasn't a vacuum line. A bad MAF also gave me symptoms similar to a vacuum leak. I unplugged the MAF and it ran better without it, so I bought a new MAF. That fixed it for awhile, then I started getting code 33.

 

Just send the injectors back in.

 

you might want to read this on the code 33
https://www.thirdgen.org/forums/tpi/...ions-here.html

 

I'm running the Southbay injectors, after I found that leak with the cold start injector mounting point, I installed the new injectors again. And, yes, there's a huge difference with the new style injectors in how it runs. The throttle response is amazing compared to the old style it had. Now gotta rid myself of code 33 and I'll be happy.

 

Did you do that block plug sold by Hawk's, or just left it in but disconnected? I know the ECM has to be programmed to forget about that 9th injector as it may/will cause a CEL, but I am curious if it affects anything else, i.e. mileage, driveability...

 

The csi is independent from the ecm and just consists of a timer switch and the csi and is used to aid cold starting and will not cause the mil to come on.

 

Thank You kind sir!

 

I bought the block off kit from Hawks. I just test drove it again, code 33, stumbling at light throttle, and one of my new headlights is out. I just wonder when I've had enough? This weekend I plan to go over the whole thing again, and if I don't fix it, it will sit. This must be why it only had 46,000 miles when I got it. CURSED.

 

when the code 33 hit's the car will go into limp home mode. In 86 the memcal with aum had drive ability issues with just the .bin in the eprom and can easly be reprogramed.

http://www.gmtips.com/3rd-degree/dox/tips/ecm/prom.htm

 

Hi, thanks for the info. I have replaced my memcal with one from a guy on ebay. Seller is Valleytek. I bought it for $89, it's the 89 $6e mask code. Driveability got way way better, but still getting that stumbling under light throttle and the light comes on awhile, then goes out. With the old 86 Prom, it would go into limp mode and I'd have a heck of a time getting home. Honestly, seems much worse when the air gets cold outside.

 

sounds like its time to start data logging , You might watch the mat and tps for issues.

 

I agree, I need to buy an aldl cable to hook to my laptop. I have an old autoxray 240 I've been using to retrieve codes. The TPS sensor is less than 6 months old, but I know that might not mean anything. I tried bumping it up to .62 but didn't seem to matter. The CTS sensor is new as well. I've never touched the MAT though.

o2 sensor is newer, too. When I got the car there was just a gaping hole where it was supposed to be LOL
I've also capped off the EGR to rule that out.

 

I would lower down the tps to .54 it sounds like when it 's doing the bog its even richer.

 

Yea, I had it at .54, did the reset on the IAC valve (that whole procedure) and put it right at .54.

 

It could be a bad ecm, but usually when the 165 ecm fails the car runs like crud all the time or when you hit a hard bump the circuit bard flexes. You can tap the ecm with a screw driver handle and see if the car stubbles at idle.