Thanks to this board, Porkyzilla (and myself) have hooked up via email/phone and will wade thru the diagnostic pool and get my Iroc out of the garage. Eric's first sugg. pull the battery and alternator to check for proper operation...will do

 

Scanner was showing 11.4 volts for battery as well as f.p.

I am pretty sure tpi's don't like low voltage.

 

I wasn't aware your 'maro was stuck in the garage.
What's the main problem?

 

Del-

Well, it used to run. Before I had a smog inspect about two months ago, I used T.B. cleaner and might of messed it up. After driving on the freeway too downtown Sac, the idle started a severe hunting problem; rev's swinging from 500 rpm to like 2500 rpm...no codes. Then, while troubleshooting; decided to stab in my first cam and rockers. Been in the garage since. It will start up though....

 

Battery and Alternator checked out o.k.



next will be maf.

 

before you cleaned the tb was it running ok? how did you clean it on or off the car? other than idle does it drive ok

what Im thinking is your tb may have been real dirty and when you cleaned it it through off the IAC that had adjusted to the dirty tb

 

The car ran good before the throttlebody cleaner. I cleaned it while the motor was running...didn't seem very dirty. since this fiasco, I have a new tps,iac,plugs,cap,rotor,afpr.

tested:

module
injectors
f.p.
fuel pressure

car will not throw codes. has not left the garage since the cam install which went o.k., but the rockers need more adj.

still thinking it is maf. I hope Eric will have some ideas once we gwet into it.

 

The car will run, even idle w/maf disconnected. my scanner showed only 11.4 volts for battery and fuel pump voltage while the idle oscillated from 500rpm-2500rpm. Took in the battery and alternator...both passed tests.

 

Ohh I see.
What about these. ..
PCV?
O2 sensor?
Ignition coil?
Vaccuum leaks?
If you haven't disconnected and reset your ECM that would be a good thing to do too.
Maybe the computer is whack.
I'm sure a scantool would help.
Running really lean?
I woulda thought fuel pump/injectors or MAF, but I'm no mechanic, just taking some educated guesses.
Good luck and keep us posted.

 

well david when ever you need ill come over and we will diagnose

 

Although I don't have TPI, here is my 2 cents anyway. My car was doing the same idle hunting, I changed everything, even put in a new motor since the old one crapped out, still had the same problems when I fired up the new motor. Finally put in a new computer and prom chip and everything is fine and runs like new. The O2 is another thing I replaced and seemed to really help smooth the idle out, just a few thoughts for you, hope it works out.

 

Sorry I haven't gotten back to this yet...I had a busy weekend and didn't touch the car. I will try to test a different maf this week. Also, I have a voltage draw because on a fully charged battery I had a voltage reading of 12.51 w/leads attached. Now, three days later it's 12.32 hmnnn. I have no stereo either.

 

o.k., I finally had time to put on another maf sensor. Guess what? car still hunts for idle. I am done. My head is clouded with different test procedures on just about everything. I am giving up. I will call Eric (Porkyzilla) and see if he can come over and take a look.

 

Don't just up and give up on her, I've been in your situation quite a few times and it is always something really stupid like an electrical short or something.

Getting Eric's help is a good idea, 2 drunk mechanics are better than 1

 

the party is afterwards


sometimes you have to think outside the box ill bring all ive got

give me a call david

 

so the car is just hunting for Idle?

I would check these first
-MAF
-TPS
-IAC
-O2
-CTS/ECT
-fuel pressure
-injector(out of car)
-timing?
-IAT?

GM did have problems with the early TPI ECM's you can check that too just unbolt it but leave it all plugged up and have the car running and just sqeeze the ECM if anything changes its bad. I don't think its you ECM if all you did was clean the TB I would think its the IAC or MAF

 

i think its unrelated just happend at the same time

 

As I posted in a earlier post, I had the same idle hunting problem, racked my brain forever and replaced everything. Finally we changed the computer and prom chip and it solved the problem, check them out as Terrell said. Oh, fyi, we first replaced the computer and that helped a little bit, then we did the prom chip and that's what solved all of my problems.

 

At this point, it is hard to tell what happened. I have replaced the following:

tps
iac
injectors.
plugs
fpr.

I can't even tell if all 8 are firing. It sounds like it, but maybe the idle is just real lopey. only thing not replaced was the o2, but the scanner shows it cycling. BUT....THE CHARGING SYSTEM SEEMS NOT RIGHT.

 

The alternator and battery have been checked out, but the gauge in the car is at like 10 volts; not it's usual 13 ?

 

I

 

Another weird thing has shown up during this idle hunting...when grounding the aldl for service mode, my primary fan would not come on. I

 

Sorry for the incomplete posts...can't even type right now; I keep hitting the enter key on accident.

 

my altenator gauge is off sometimes it shows 10 but when i get my volt meter its 14 its just a bad ground somewhere than

 

You said the problem happened before the cam right?
Otherwise that's a whole 'nother can of worms to diagnose.
That is definitely going to change your idle in general, depending on the cam of course.
I believe you said zz4 which is 'sposed to be a good stock replacement, but it shouldn't be THAT lopey.

 

Yes, the symptoms where before the cam install. The cam that went in was a lt4-hotcam (i already had the zz4 motor)

 

Don't know if it will pertain to you but when I had Alex's car it would idle at 700 then all of a sudded jump to like 2000-2500 rpm for about 5 seconds.It did that steady.I then noticed that whenever it would idle up his a/c compressor was kicking on boosting the rpm's and would shut off letting it idle back down,I unplugged the compressor and it was fixed,just something else to add to your list.

 

I always defalt to vacuum leaks for this kind of thing but then, I am a computer nerd.

Speaking of which, I have an extra (OEM) PROM for an 7747 ECM. If this is where the problem lies (Will's guess) then this may not help given we have the same ECM. However, this may help as a band aid instead:

TBI Chips

As with everything mechanical I suggest, take it for what it is worth: A Wild *** Guess.

 

I'm gonna' try unplugging the a/c first.

I really don't think it's the chip or ecm. My chip is years old and made for the zz4 swap.

how much vacum should the motor be pulling at the base intake? I have a vacum gauge.

 

I really feel the answer will be known through data logging.

 

If you get a chance, go over to e-rip-off and see the 73' monte carlo ss I have been bidding on...sweet!!! triple black up to like 8100.00 I have bid 11k no dice yet.

 

I guess for giggles I could swap in my stock prom.

 

I agree, try putting in the stock prom chip and let us know what happens. Oh, did you try unplugging the AC yet, how did it go?

 

Hey Will-

No, haven't done the a/c unplug or chip thing yet. I am at work still. Lately it has been very hard mustering up the energy to work on the money pit. I do know a few here are following along, so to appease all of us I will trudge on. I will status after the swap and unplug.

 

I've done all the above.....Erik your up to bat. I will call you this eve to see what your schedule looks like.


I really miss driving the Rock

 

Dang man, can't believe it's still giving you trouble, that really sucks. Hope Eric can help you out and get this issue resolved soon, keep us updated.