I am new here. I found this place after doing a google on crossfire Camaro tech.
from just looking around a little it seems I have stumbled upon a wealth of knowledge. which prompts me to ask a few questions.
I have an 82 Z28 with the LU5 305 "7". the lovely crossfire set-up. who knows about these things? anyone know the IAC strategy? I have an interesting history on this car which has included a very long list of neglect and incorrect repair. now I get to fix all this hopefully someone here can help me.

 

I dunno man, that crossfire induction is not real popular among gearheads...info on it around here might be tight but good luck with it.

 

There's Crossfire info on TGO, and it's really just TBI atop a tuned port intake manifold.... so it's very applicable here (TBI and 3rdgen Fcar). Use the search button above. The Crossfire Vault (another web site) will have even more info specific to the CFI (Crossfire Injection) so between that site and this one, you're very well covered.

 

How to fix it?? Remove all the CFI components and send them to me, and I'll send you my Holley carb in return

What exactly is wrong with it? How were the repairs done incorrectly??

 

what's this "TGO" ?
I am actually working on this for a customer of mine. he has had this thing for quite a few years. I think he said it has been about 10 or so. he doesnt drive it much at all. from the outside it looks like new. about 2 years ago the cam went flat so he had a guy who "knows what he is doing" replace it. it hasnt run right since. first thing I found was a bad CTS, then O2 sensor, distributor not installed correct, plug wires mixed up and laying across the top of engine and AIR manifolds, corroded ECM, vacuum leaks along with old gasket material on both the upper and lower plenums. I fixed all those to still have the same problem. it would not run unless I feathered the throttle and was absolutely gutless. it was acting like it was WAY lean yet the smoke check showed no leaks and the EGR was blocked off. I then started to re-think he whole situation and came up with the theory that it must be something mechanical. I pulled the pushrods and did a leakdown test with good results. less than 15% on all 8. OK, what does the cam look like? out it came to find all the lobes with considerable wear and lifters turned concave. at this time I was unable to determine if this was even the correct cam as was the customer. time for some new known correct parts. the cam swap went smoothly ( I even replaced the bad alternator along with fixing the disabled AIR system). I fired it up and broke in the cam ( my initial startups ALWAYS work on the first try) with pleaseant results. after the 20 minutes I brought her back down and she ran smoothly. then the test drive became dissapointing. it was low on power but nowhere near as bad as before. under WOT it ran nice and strong but part throttle was lean and had developed a significant missfire on 4 cylinders. #s 2,4,6,& 8 were dojng next to nothing. while spraying around with carb cleaner i found while lightly dribbling it into the rear throttle body she cleaned right up while the front made no change. the front was using all the fuel leaving little for the rear (the right bank). I then tsted the fuel pressure to get a steady 10PSI, even with the return pinched off. bad fuel pump. I replaced that and noticed a great improvement on power. she runs out real nice. ( these things can haul a$$). but the idle is staying about 1000 RPMs warm or cold. I tried partially plugging the IAC ports rith shop rags only to find the counts increase. it wants it up there?! further checking revealed the front IAC opens before start then closes after it is running while the rear is the opposite. at a warm idle it is at around 12-16 IAC counts. I should also mention how it seems to run rich and has a steady 1.5V MAP signal. I know this may be trivial but I believe the MAP should be about 1.2V.
does anyone have any insight? I am about to the end of my rope on this thing. flipping burgers is starting to look like a good career change.

 

ThirdGen.Org

 

 

Sounds like the previous mechanic really messed things up...
As far as MAP sensor goes, are you getting any error codes, either a 33 or 34 error code?
Also if you are running rich you should get a code 45.

If you get a code 33, Map sensor voltage it too high. Clear all codes if any, disconnect the MAP and do not ground the diagnostic terminal. Start the car and wait for the check engine light to come on. Turn off the car but keep the ingintion in the "ON " position. Ground the diagnostic terminal. If you're getting a code 34 and the vaccum line is ok to the MAP then you will need to replace the sensor. If you get a code 33, you will have to check some circuits for an open ground. Circuit 469 which is the the "A" terminal to the MAP. This leads to the white connector to the ECM which is number 14 on the connector pinout. This terminal is the ground. Circuit 432 is the "B" terminal to the MAP. This is the signal terminal and leads to the black connector to the ECM which is number 20 on the pinout. If there is a short to voltage on this circuit, the ECM needs to be replaced.

If you get a code 34 alternately you can do the same start procedures but put a jumper connecting pins "B" to "C", ground the diagnostic terminal and check the code. If you get a 33, Replace the MAP sensor, if you get a 34 remove the jumper and check voltage between pins "A" and "C". "A" is the ground, "C" is the 5 volt reference signal. If you get below 4 volts, check for short or ground in the "C" terminal, white ECM connector pin 11. If the circuit is ok you have a faulty connector or ECM. If you have 4 to 6 volts, disconnect the Black ECM connector and check for a open or short to ground at the "B" terminal, which is the ground. If that circuit is ok, you have a faulty connector or bad ECM.

These procedures seem to counterdict each other since in the first part if you get a code 34 you replace the MAP, and the second part if you get a 33 you replace the MAP. I guess you could try each and see what happens. I have the electrical schematics if you need them, and the ECM pinouts also. I know trying to describe them probably wont really help you out as much unless you know what you are looking for. I hope this helps!

I also just checked the voltage for the MAP sensor. With the engine running, but the throttle plates closed, the ECM should get a signal of approximatley 1.5 volts. With the car on, but engine off it should be around 4.9 volts. This is the reference signal to the ECM for barometric pressure. If you are getting a 1.5v signal this is right on. At WOT it should be very close to the 5.0v. A dissconnected MAP will give a lean signal. A shorted MAP or disconnected, cracked, leaking hose will give a rich signal. I'd check the hoses first hand, then check for shorts. Most likely it is a bad MAP.

 

This sounds like you might have a vaccum leak. If you plug the IAC ports the RPM's should drop. If they are staying up you have a leak somewhere. Maybe the rags didn't make a seal 100%. They make a special tool to plug them, or you could just put some duct tape over them. When the IAC is fully seated, it is the zero reference position and the ECM records this everytime the VSS tells the ECM that 30mph has been reached. At this point the ECM records zero reference and signals the IAC to retract a specific distance based on coolant temp. When the engine is off, the ECM signals the IAC to position itself for the next engine crank. After cranking the IAC is extended to a position determined by ECM based on coolant temp. Except for this movement at engine shutdown, and just before startup the ECM will not order the IAC motor to move when the car is in park or neutral. This was susposed to have been changed in the '83+ model years. Also, if you disconnect the battery alot, the ECM will have to "re-learn" the best IAC positions and may also add to a high idle. I hope this helps.

 

now we're talking
I intentionally plugged the ports only partway to see if it would try to bring it up. and it did.
so you're saying the 82 only tunes the IAC when in gear? why is the front one the only one moving prior to start-up and the rear is taking over afterwards? should I just tell the guy to drive the car for a week or so in an attempt to re-learn idle strategy? I have ZERO vacuum leaks and the EGR is not causing this. (the 2 things I look at first when an idle problem is present)

 

What camshaft did you put back in?

 

good news, I found and fixed the problem.
I used my Thexton IAC tester and extended both IACs then started the engine (opening the throttle a litle of course). she idled nicely at about 650. then U opened the throttle and brought the speed up to about 2000 RPMs. both IACs retracted as expected and at the same speed and amount. then I let off the throttle. the front extended to the closed position while the rear didnt move at all. hmmmmm..... another look at the wiring diagram showing bot valves on paralell circuits, hmmmmm... so I pulled away the looming from between both valves to find a splice with a broken joint leading tho the rear. I repaired this with a soldering gun and PRESTO!!! she idles and runs like new.
I took it for a good test drive for a re-learn and called the customer. he is EXTREMELY happy he gets his car back and gets to enjoy it for a while before the snow hits. I think I am even happier, I just removed what was has possibly been the biggest hemerhoid ever from my butt.
I must confess though, I hate to see the car go. I want one just like it. these are fun and fit me nicely.

a big thank you is in order for this board. if you guys dont mind I would like to hang around. I think I may be of help and could even gain some knowledge if I snoop around. now where are these threads about burning our own chips?.....

 

You did a lot of troubleshooting, something that seldom gets done here.... so I think it would be great for all of us if you hung around for a while.

 

where are these threads about burning our own chips?.....

Start with the (Come in for a FREE tune) sticky at the top of the TBI section

 

and then look at the forum + stickies here:

https://www.thirdgen.org/forums/diy-prom/

 

Glad you found out the problem...not many people want to try and work on CFI cars, they are "too hard" to work on

 

I'll take on anything. I seem to get the trouble cars that other shops cant figure out. I can even fix a Fiat. (I almost got fired for taking that one in)