My son bought 1988 firebird,2.8l multi port fi. Checking it out and seems it runs rough. Not too bad if you throttle it up but hard start,long crank and idles rough. Blink code for lean condition code 44. Did tune up, the norm like cap rotor plugs wires and fuel filter and no change. I then noticed the left exhaust manifold was not hot after running,can place hand on it after running two minutes. The right side very hot will burn to the touch. I'm think bad injectors? It would explain the long crank hard start, rough idle,lean condition and left exhaust not too hot. At least this my thought. Ideas?
Thanks,
Jim

Hope I gave enough info

 

Check fuse panel and see INJ fuses, maybe blown. I can't see three injectors being bad on that bank. It must not be getting the signal to fire the injectors

 

Good idea. I did check fuses earlier and did not see any for injectors.looked at drivers kick panel fuse board. Another place? I am thinking injectors bad, maybe not all 3 on left bank but i dont think just one bad would guve me this condition? But then again its smooth when you throtle it up. That side gets hot but not hot enough to lead me to believe all injectors working.

 

I assume there will be two fuses for injectors? Left and right bank?
Thanks

 

It is for V8 TPI, not sure for V6

 

Its showing 2 fuses

 

Nice thanks! You da man!

 

Now that I have light I found them. 10 amp. One is inj 1, the other f/p injector 2. I assume fuel pump and injectors. Both fuses good with test light

 

Do you have a set of Noid lights to check injectors to see if they are getting the command?

 

I have noids for throttle body injectors only, not for multi port

 

I have injectors out. Looking to be like a common rail kind of thing. All injectors ohm at 16.3 or 16.4. That looks to be ok as chart shows 12 min. I assume 12 ohms minimum.Chart shows it under Chevy 1985-00. . Under Pontiac it just shows a 1993 at 11.8-12.6.
Next need to check voltage to them

 

looks good so far. Need to see if they are clogged. Are they getting voltage.There is a procedure on here on how to test them. Pull the fuel injectors out of the intake and get lotsa rags and turn key to on position and see if they spray.

edit: see you're checking for voltage

 

I can buy rebuilt set for $89 . As long as injectors are out im thinking of picking them up. Kind of a pain getting them out

 

Can't really test them as its entire unit. Fuel lines on top have to be removed to get it out. I might be able to pull unit and connect back wiring harness to see if each injector cycles . I'm just getting rebuilt ones.
I really have to believe there is an injector issue with symptoms I've described. Can't imagine what else it could be . If he new injectors don't cure it I'll look at feed to them

 

Looking at the schematics that bob88gta was kind enough to supply, I'm trying to figure out how the ecm fires injectors for each cylinder? Are they hot all the time and the ecm grounds them to fire? The single wire in and out has me baffled??

 

You are reading schematic correctly, it is batch fire.

 

My firebird was the same why. My problem was the mass air flow sensor. You could try unplugging that and see if it starts normal.

 

Noah
But how would that explain the left side exhaust manifold not being hot? I don't think It can. Someone check me here but the only thing I believe could cause that would be that side not firing/ getting fuel.
Mass air flow yes may be good idea after injectors.

 

Batch fire? As in each side injectors all fire at same time?

 

I'm gonna be honest, I'm not much of a mechanic. It just sounded a lot like my problem, which was fixed by unplugging the mass air flow sensor. Good luck in finding your answer!

 

Hi Lakepirate ,

No need of making this harder than it need be , get a noid light on the side with the cold manifold and see if the spray signal is actually being sent . Sure , could be clogged injectors . Just as easily could be a bad output from the ECM feeding that bank of injectors too . Wouldn't it suck to pay close to $100 to replace injectors that may be Ok , and just not getting a signal ?

And yes , you are reading the schematic right , it supplies constant +12 volts to the injectors whenever the key is on , through fuses "INJ 1" and "INJ 2" . The ECM grounds the negative going side of the injectors in a pulsing manner to spray fuel . Since you see two separate banks of injectors wired to the ECM , it's quite reasonable to believe a failure in one bank's output could cause the exact problem you describe .

The noid never lies , and will tell you all you need to know ....

 

Obird,

Ive used noids on tbi, not on mpfi so I'd have to buy correct ones. Hey if they are original injectors I don't mind the $89 bucks.
I'm thinking why can't I just test each injector feed with dvom with key on?

 

Ok I'm an idiot! I looked at my test noids for tbi and remembered its a whole blue point kit. Ha! I've just only ever used the tbi. It has about 8 test noids. One looks like it will work.
Obird, thanks for the too. I'll text and let you guys know
Thanks!!!

 

good luck....I'm waiting for some good news

 

As one injector bank fuse also looks to power the fuel pump, I'm going to see if I can disconnect at rear the harness to fuel pump then use noids to check for voltage to injectors. If I don't disable fuel pump with fuel lines off I'll get a bath when testing

 

I checked each injector tonight. I forgot I had a multi port pulse tester. All injectors react at least. Can't tell if a few are clogged but at least they all have same resistance and they all seem to work.
When new injectors come, I'll install them and check feed to them with the noids. Gotta crank motor for this so I'll have to wait until new ones come

 

I'm not sure where your seeing this , but no , neither injector fuse involves the pump . If you look at Bob's diagram , the pump is the device being called "fuel tank unit" and is fed power from "inline fuse #3" (20 amp fuse mounted on the fender under the hood) , through an orange wire to the fuel pump relay and oil pressure switch (which are wired in parallel) and then on to the pump itself through the tan/white wire . the fuses "Inj #1" and "Inj #2" each feed a bank of 3 injectors only , with no other power sources for any device being derived from them .

 

The schematic is too blurred for me. On iPhone, should really go print it off laptop. Yeah did not make sense to have both one bank of inj and fuel pump on only 10 fuse. I thought possibly as one fuse is labeled inj 2 f/p. And when I pulled that fuse yep, fuel pump still did two second prime

 

Ok update
Feed to injectors test fine per noids . All flicker nice. Installed new injectors. No change. Thought.... Now the egr valve is in the right side exhaust manifold. Maybe that explains why it get hotter than left? Don't know.
Went back to basics and checked timing. Oh it's at about 25% before tdc so I'll have to change that. The ruff idle and hard start may be more fuel starvation( need to check fuel pressure) or maybe bad egr
Someone check me. Am I missing anything?
Thanks

 

ok another update. I confess I pulled the ultimate bone head move but first. I found the 4 wire connector not pushed in all the way on the distributor.Tried pushing it in, no go,its cocked. Pulled it out and one pin is bent.Thats why connector would not go in. Also distributor horrible rusty mess, corrosion etc. Figure this must be source of the poor running condition.
Buy new distributor,put it in but dropped the hold down bolt. Heres the bad part, got impatient and cranked engine over to see if it ran better. Distributor popped out. Cant get it back it. Figured oil pump shaft out of phase.No, even with oil pump shaft out it wont go in all the way. Old distributor wont go in either. Pukes oil, has about 1/4' inch gap. Maybe a little less. Now the timing is totally screwed up but the thing still should drop in. I should not have to bump motor get get distributor in all the with no oil pump shaft correct?
The old distributor had black RTV silicone around it's base. Wondering if old distributor never fit correctly and thats why it was siliconed. Makes no sense!!