Ok so I have a 1983 trans am with the crossfire injection system. It is running very very lean, and throwing a check engine light. The check engine light says its the O2 sensor, which I replaced and its still doing it . So I took it to a friends shop, he has had it for over a week now, and cannot seem to find out what is wrong. The diagnostic machine said check grounds and ecm, but they all seem to check out ok, and the Ecm, is doing what it is supposed to be doing. We then replaced the fuel filter and checked the fuel pressure, fuel pressure at idle is 10psi, california cars should run around 9psi from the factory. So its not the pump. But when you give it gas, it just drowns itself, boggs down and acts like it is miss firing , no one can figure out whats wrong, ANYONE know anything ????? Had the same problem ? all the plugs and plug wires are changed and it idles fine ..................

 

Make sure the bolts on the intake manifold's top plate are tight. They are notorious for getting loose which will give your Crossfire a MASSIVE vacuum leak.

 

I will have them check that first thing in the morning, it starts and idles fine, and the timing is fine and they have checked all the sensors, and I replaced the O2, so I will see if thats the problem, but it boggs down and acts like it is missfiring when the gas pedal is pressed. I thought it might be the throttle position sensor, but that checked out fine .

 

Is it stock? any mods?

 

Completely stock, no mods at all

 

Anyone else have any ideas at all ????

 

ok this morning they checked for vacuum leaks, and checked the map sensor, also checked the distributor , all are working fine or no leaks ,the shop is at a loss !!! Help folks before my car ends up going for parts

 

Did they tighten the bolts on the intake? I had similar problems with mine until I did that.

 

well, I will make sure they tighten them in the morning, or check and see if they are loose, but they said they tested it for vacuum leaks and found none

 

its crazy, cuts they have almost given up trying to find out whats wrong, they have went almost every avenue ????? which sucks, cause I dont wanna take this thing off the street,

 

ok, So , they are stumped, all but given up on the car, it wont stay in closed loop, it runs like crap in open loop, then every great once in a while, it will go into closed loop for 3-4 mins and run great, then falls on its face and goes back into open loop, very crazy

 

IS IT ACTUALLY RUNNING LEAN?!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Check if it's not pig rich first, a leak in the exhaust upstream of the O2 sensor, a faulty air diverter valve or switch solenoid, a leaking or stuck air tube check valve...all sources of possible air introduction upstream of O2 sensor, triggering a code.

I assume yours is setting a lean code?

Why would it go out of closed loop? With most codes set it will not stay in closed loop, it'll go into limp mode, an O2 code will certainly do that

Pull the CTS connector, wire up a 520 OHM resistor so it will stay in open loop (fake cold CTS signal) and see what it does.

FP is 10psi at idle....but what does it do when you blip the throttle?

 

they are saying its running very very lean on the drivers side bank of cylinders, they have checked for every kind of vacuum leak , and nothing anywhere, the passenger side cylinders are fine, its only on the drivers side, fuel pressure regulator maybe ???? I thought maybe the regulator is bad and its throwing the o2 sensor ? just a thought, but they have given up on it now, I dont know what to do

 

they tested the fuel pressure , and its 10 1/2 psi at idle, said its just fine, didnt test it at throttle

 

The pressure regulator regulates both TBs, the pass side one just has an accumulator.
If it's one bank that runs lean it can't be that.

There are some ports on the manifold that are suspect, have they checked those for vac. leaks? I mean the ones that screw into the lid behind the TB and maybe the PCV hookup.

Also check for a sticking EGR valve although that should show an issue with all cylinders and mostly the rear ones

Is the injector working OK? Maybe it's clogged? Is the spray pattern the same as the other side? use a strobe to check (easy way to do it just hookup the timing light and shine into the spray pattern)

 

Have the shop "dead head" the the pressure gage. I would be willing to bet that 10 is all she's got, it should be able to make 18-20 if you pinch the line after the pressure tap. My first cfi was making 11 at idle with lean miss on hard accel. pinched the hose and it would not go up. After much debate with my boss him saying "book spec is 9-13" he finly got me a pump, after installing it, pressure was at 12, would deadhead at 18-20...Wow cfi can make POWER. on my next cfi motor (82 t/a) when it was running lean first check...fuel pressure 10 psi no change dead head new pump, and power was back. your friend is not wrong to move on to the next step BUT cfi is different, if you don't have 12 psi it will run lean. good luck, pulling the tank is a pain, I have read that using a later tpi pump will work, and give a greater reserve, haven't tried it, but sounds o.k.

 

If you need a new pump, get a TPI pump, it's much more capable than the TBI pump. No the FPR diaphragm will not rupture and no the pressure won't be too high. The pump only creates flow and the regulator determines the pressure. Dead head pressure is max. press attained due to max flow/max fuel crammed into a dead head restriction. That is a lot higher for the TPI pump. With your TBI system the pump will have a much easier job supplying fuel demand

 

I checked the fuel pressure on my wife's 83 cfi today. so I took some pictures to show what I mean.G.M. says to check between the throttle bodies. unless there is a restriction in the pas. side it should make little difference. these were taken at idle



the needle nose are after the "T"
I Hope Your car gets sorted out, it is a shame that the crossfires are so misunderstood.

 

shop gave up on it today, told me to come get it , it wont pass smog , now its just sitting , it runs, but when you press on the accelerator , it acts like its starving for fuel, sometimes it runs good, sometimes it doesnt . very very wierd

 

@ Twin_Turbo , WTF !! The A.I.R ystem can actually go bad and cause a rich condition ? please explain more .

 

This may sound "*******ish", but no competent shop would just give up on any car. They must not be very good mechanics if they do. Any true mechanic will find the problem, may take a bit, but they WILL find it. Check all sensors.

 

Yes, the air system pumps air into the exhaust manifold tubes in open loop and the switching valve reroutes to the cat con in closed loop. If it doesn't work properly and air gets into the manifolds the O2 sensor will register it and see it as a lean condition, excess oxygen means too little fuel. The car will start to run rich as a result.

We still don't have a definitive answer here whether it'srunning lean or rich, I also find it hard to beleive it's one bank of cyls. The CFI is a largeopen plenum, sure one injector dominantly serves one side but if there is a fuel delivery issue it should show up on both sides.

Are both injectors working?

There's a reason why the thing goes out of closed loop. IMO prime suspect is the CTS sensor & connector. If corroded/bad connection the resistance value will read too high, the ECM will think the coolant is mighty cold and excess fuel will cause problems too.

 

they swear up and down that its running lean, if the thing runs fine in closed loop, I would seem to think the coolant temperature sensor is the problem too . However, the shop told me they checked every sensor on the car, and they are all working just fine, they also said they checked the ECM, and we even replaced it with a reman one, just to see, and it didnt make a difference. They said they smoke tested it and checked for vacuum leaks everywhere and there are no leaks anywhere . Very very wierd, I have it at a new shop now, with a GM mechanic who worked on these in the eighties , so we will see what happens.

 

both injectors are working and spraying just fine , is what they told me, and I checked them myself, and they seem to be working just fine,

 

If it runs fine in closed loop it obviously is an open loop problem.

So now that we know this we have to check what paramters/sensors affct fuel delivery in open loop.

They are:

collant temp
TPS signal
MAP signal

That's it. The TPS and MAP are not suspect since they operate properly in closed loop. CTS signal is there, it allows closed loop but it could be off. Measure the resistance over the sensor and compare to coolant temp.

Coolant Sensor Resistance

Engine Temperature.......Resistance
(degrees F)....(degrees C).....(ohms)
210 99 185
160 71 450
100 38 1800
70 21 3400
40 4 7500
20 -7 13500
0 -18 25000
-40 -40 100700

Now we have to look at what could possible introduce air into the intake system in open loop that would screw up fuel ratio, and this would not be picked up by the O2 sensor because it's not hot enough to create a voltage signal (chemical potential)

One suspect might be the EGR solenoid, another the purge solenoid. They are electrically operated vacuum switches. Maybe one is leaking.

Check the EGR too, see if it operates properly. If in doubt pull all the vac. accessories from the engine, plug off the ports and only leave the MAP connected.

Are the center ports on the TBs plugged off? They only draw very little timed/venturi vacuum (slit in TB lines up w/ throttle plate) these are for balancing the TBs only but should be plugged.

If the car goes in open loop, check the BLM and INT numbers. Is the ECM activly adjusting fuel metering for a lean condition? This could indicate a lean condition that is present in open loop too but not taken care of because there's no O2 sensor feedback

Do you have sniffer probe numbers? if it's running severely lean, HC numbers should be up because of lean misfires What are the rest of the numbers?

Does the shop have a wideband system they can use to properly diagnose AF ratio?

 

Good luck with the new shop, please let us know what they find, any chance to learn something should be taken. You mentioned to me that it won't pass smog. I hope you have had it tested, and this new shop is a smog repair station, in California once you have spent $450 at a state linsenced repair shop, to repair a smog failure AFTER the car has failed you can go to the ref. and get a cost limit waverhttp://smogcheck.ca.gov/80_BARResour...e_Centers.html follow the link and read what to do, it is best to have the car running properly, but a waver could buy you more time.

 

well they didnt get to it til this afternoon and didnt have much time to spend on it, but they started putting it on the machines and such, and at this point we dont know anything, but will see, but they seemed to think the cts sensor might be a candidate , so we will see

 

ok well I have the car back home now, They didnt find one thing wrong with it , however it still isnt running right, now a shop has looked at it and a long time GM mechanic has looked at it, he did say however he thought it ran like it had bad gas in it, and it was almost empty so I filled it up with 91 octane , and drove it around for a while, it did start running better, but then ran like crap for a while, then ran good again , wierd

 

sometimes the easy answer is the right one. I hope that was all it was. Was the car sitting for a long time? run a few tanks of gas with techron added, that is the only snake oil fuel treatment that I think really helps. I would still like to knoe what your "deadhead" fuel pressure is, 10 1/2 p.s.i. sounds low for a crossfire.

 

Ive heard taht when you get alot of crud in a highmileage engine, the regular 87 octane will start detonating. Maye thats just why the higher octane helped you out.

 

OK. Drove it around again today. It ran like crap mostly. The stopped at a auto parts store and when back out and almost didn't get it started. What a nitemare.

 

They gave me a code key. Its giving me a code 44. Lean exhaust.

 

How old is the O2 sensor?

I don't believe it's bad gas just like that, especially since the bad gas apparently turns into good gas the moment the FI goes into closed loop. I think they are trying to brush you off since they don't know what the problem is

If the code is actualy your CEL should be on, it it?

The code is not holy i that it is the actual problem. It's what the ECU perceives as being out of normal parameter range. For instance, a faulty AIR system or an exhaust leak upstream of the O2 sensor will set that code too. in reality the car will run too rich.

If it's too lean and that code actually sets because of fuel delivery issues then you have to look there, water in tank, water in filter, clogged filter, clogged injectors...and so on.

 

I agree. 11 is minimum. 13-14 would be better.

 

well, The 02 sensor was changed the day after I bought the car , which was like a month ago. they have checked both injectors , said they are spraying fine. They have also replaced the fuel filter and said the pump is putting out good volume. However, I took the TPS off yesterday and had it checked, and it was possibly bad, on the test machine the test light is supposed to stay steady, and at one point it didnt, it flickered, which means its going bad off and on ????? Then I come home and put it back on and try to get a voltage reading , and nothing , I cant get a reading at all

 

the GM mechanic did say that when you blip the throttle the fuel pressure is holding steady , but didnt say how much, When I asked, he said well its putting out btwn 9.5 and 10.5, time for new fuel pump maybe ?????????????????????????

 

the check engine light comes on when coasting down a hill, then the minute you punch it or give it gas to go back up the hill, it goes off , sometimes you can punch it and it runs great, other times it wants to bog down

 

go to sears http://www.sears.com/shc/s/p_10153_1...1&blockType=G1and get a fuel pressure tester. install the tap in the fuel line. on the pas. side you will have a metal line that changes to hose the hose goes to the bottom of the fuel filter. with the engine running at idle check the pressure. if the pressure is o.k. and the car is running fine then use a set of long needle nose and pinch the hose. if the pressure does not rise to above 15 psi. your done the regulator should keep the pressure at 12-13 psi. if you don't have the pressure to go higher then there is no reserve, running around "light footing" the throttle does not require that reserve. but when pulling onto the freeway you need it.
another option is to get a can of carb spray and have a friend load the engine by putting it in gear and hold the engine to a range where you are getting bogged down. spray the carb sprat in the hole on the top of the air cleaner. if the engine picks up, you are running lean(see option 1) if not or if it bogs worse, you might be over fueling, if that is the case, disable the air injection by plugging the hose going to the driver's side manifould, that should be the one with the o2 sensor, and try driving, if it is better, you might need a diverter valve, they are not cheep, so give yourself a week or so to be sure.
Also if you suspect the T.P.S., try unplugging it, the car will run, if it is better, get a new tps. hopefully one of these tricks will help you get your car back.

 

ok well I have my car back, I suspected along with some other folks here that it was the fuel pump, but the shops kept telling me it wasnt, I had a feeling it was, so I took it to a friends house and after 7 1/2 hours we got it changed, with a pump that puts out a minimum of 12 psi, guess what folks, this thing runs like a new car, what a difference, its still throwing a check engine light, but thats only because of the TPS being bad , but it still responds , and runs very very very well, no more codes for lean exhaust, the fuel pump was the original one, and the screen was black and crumbling, along with the connector hose that was cracked. This thing hauls major *** now. I have a new TPS on order, be here Tuesday, then it will pass smog and be good to go. Thanks to you guys its fixed, imagine that, we figured it out, not the shops, now I know where to go .

Thanks again guys !!!

 

Another CFI running strong. Good to hear!

 

it passed smog today, its ready to go , dont have to worry about smog now for another 2 years, I am so glad, now if I can only pry my wife out of the drivers seat, cause this car will now catch a 2nd and a 3rd, lol, especially with her driving it , LOL

 

I hate to say "I told you so" but...
all kidding aside it is good to hear that another crossfire is running as it should. I firmly believe that the combo of the fuel pressure spec gm gives being wrong(and never updated with a t.s.b.) and that gm can't seem to build a fuel pump to save its life is the cause of the bad rep that crossfire has been plagued with. I wonder how many were needlessly "balanced" when they were suffering from low fuel pressure.
If the first shop you took it to is really a friend, let him know how you fixed it. Maybe they will learn from past mistakes and what they are looking for when hooking up a fuel pressure gage.

 

happy ending

 

So when I went by the first shop, to tell them I actually fixed the car myself, and the 2nd shop didnt fix it , they were amazed, lol. But said they were just going by specs, and I said well this proves , specs arent always right , listen to the people, not the books sometimes , lol

 

There's pressure and flow spec's.
Mine is 40.5-47 psi engine off and 1/2 pint or more in 15 seconds, or 1 gal in 2 minutes.

 

so how is she still ruinning?

 

Hay I have a 82 trans am doing the same thing, you may want to change fuel press regulator. You have two on there.