yetterben

I will make a long story short. Picked up a 92 rs some idiots had ahold if it. They decided to start screwing with ****. Egr vacuum and map vacuum was all messed up. Prior to this car ran like crap well no wonder lol. got new lines and plumbed it all the correct way.

Still have no figured out where the vacume line from the heater pot under the hood goes. Assume it plumbs into the firewall.

Anyway car idles pretty goos around 1,000 who knows with are tach. Any way sometimes it will just up to 1,500 on its own. Sometimes it surges. Unplugging the cts sometimes make's it behave most times not. I have re adjusted the idle via the fsm. Pretty sure there is no vacume leak's all lines new. What should i look for here. TPS....... Its not all the time the car can idle fine for 20 minutes and then just to decide to rev up.


Also what the big nipple on the back of the intake go to. Its plugged off. I have not been around a sbc in years.

RFmaster

Yetterben

Welcome to TGO

The big nipple between TB and dizzy is used for AC vacuum controls and brake booster. It should be connected or plugged!
The MAP sensor uses back side TB vacuum port. Front side TB vacuum connections are used for EGR, AIR, CCP, and PVC. If you do a search I think there is a vacuum interconnection diagram here.
Sudden idle surges can attributed to a number of things. Check for vacuum leaks - TB to intake manifold can be leaking, IAC can be all plugged up and sticky or EGR valve passage can be full of carbon. R&R, clean and verify. TPS can be checked without removing it from TB. Stock engine should be idling around 650-700 RPM.

//RF

yetterben

I also wanted to ad they removed as bunch of the air stuff. Brass plugs in the exhaust mani and no air pump that i can see. Only thing i can sort of base this system from is my 94 burb and my 99 ta which is vastly different. IS it hurting anything without the air pump setup? they hacked the cat off too.

Also when i stick my finger down into the iac it sounds and kinda feels like vacuum. has no affect on engine. Of course i got a fat finger......

RFmaster

That's one hacked Camaro you got yourself there.

If AIR was removed and exhaust manifold taps were 'plugged' well you should have no problems. With that in mind listen for tail tale exhaust leaks. Exhaust leak will screw up O sensor readings and will affect idle quality.

Based on your description - IAC missing - you have one huge vacuum leak. Get a replacement and reconnect it to the system (ECM control).

And do us all a favor by breaking morons hands for bastardizing the engine management. It works just fine in its stock form.

//RF

yetterben

there is a iac but when i stick my hand isnde the orifice in the tb is what i ment lol.

yetterben

Well i went out and pulled codes i got 15 22 23 and 34. No either everyone is bad or its because i had them all disconnected at one point in time while the engine was running causing a cel.

Also i dont know how far the iac is supposed to kick out but it did kick out when i looked down there. There is a loud hissing noise coming from that pocket where the iac is. I jammed my finger down there and the car killed 10 seconds later.

yetterben

New info lol. As it is surging the iac valve is moving in and out. Is it compensating for something? At first i thought it was the maf it was not bolted back down to the firewall. Bolted it back up and all was fine for a few seconds. Than it started again. Then i removed the vaccum line plugged it all was fine for a few seconds then i unplugged connector same thing. Idid get a throttle body gasket and egr gasket. Another thing i think the dumb hilbillies might have jb welded the egr port All i can see is a pin hole threw the center.

yetterben

Before i put stuff back where it was supposed to be the car idled high at like 1,400 but did not surge. I also tried to squeeze the egr and it did not budge. Maybe its casue i was tired and not giving her enough sack :P

RFmaster

Code 15 Indicates that have an open connection at your CTS. CTS is located near thermostat housing and should have yellow and black wire in a two pin connector. You can check CTS without removing it from engine. Disconnect harness connector from CTS - get yourself a trusty DVM and at room temperature (22C) measure CTS resistance. It should be around 2700 Ohms at 22C resistance should drop as temperature increases. Check black wire vs. engine ground - it should be near 0 Ohms. Dumb hillbillies probably cut ground lead causing Code 15. With ignition on measure DC voltage on yellow pin to ground - it should be around 5 Volts.

Code 22 & 23 are TPS & IAT related - check gray wire which supplies + 5volts to both sensors. Also check the black wire feeding TPS, IAT, CTS - this is a ground return and if it is open it will cause 15, 22, 23.

Code 34 is a MAP sensor signal voltage was too low (high vacuum) when engine speed was over 1200 RPM which can be caused by a hacked harness. Disconnect Map connector measure connector voltage between pins C and engine ground - it should be 5Votls. Repeat the same measurement between pins A and C again you should see +5 volts. If not ground is open (black wire).

Once you take care of sensors reset IAC - use search (your homework for tonight) here on TGO.

Post your findings

//RF

yetterben

Would you not think that it set all those codes because i unplugged all that stuff one at a time while the engine was running setting the cel. I will verify for sure but its funny it threw a code for everything i pulled off. Oh asnd i have been on here all day searching

RFmaster

You can clear codes (engine off) by disconnecting battery for about 30 seconds and try again.

https://www.thirdgen.org/tpimod2

//RF

yetterben

I will check fuel pressure too but i dont think its pump related while its surging i can crack the throttle and that 305 just screams.

Also what tells the iac to pulse or adjust? What reading does the ecm need to do this? it might help me to track it down if i new what the ecm see's to adjust it like this.

RFmaster

You have to make sure that you have no SES light on.
IAC is used to maintain target idle speed - it is a controlled vacuum leak. These older ECMs however have no clue about IAC position. So establishing a known pental IAC position is important.

//RF

RFmaster

You have to make sure that you have no SES light on.
IAC is used to maintain target idle speed - it is a controlled vacuum leak. These older ECMs however have no clue about actual IAC position. So establishing a known IAC position is important.

//RF

yetterben

ses light is not on during all the surging in and out of the iac. It just goes bonkers up down up down up down. in out in out. The ecm has to grab data from somewhere to adjust it. I reset it to per the fsm on alldata.

RFmaster

Based on your description I would look for additional vacuum leaks. Stock TBI engine should have a rock steady 650 - 700 RPM idle.
Take a look at injector fuel spray. It should be nice mist, not a drip! Spayed fuel mist should hit TB bore sidewalls before being drawn into intake cavity. A small exhaust leak up stream from O2 sensor will cause idle havoc. O2 is on driver side. Check for AIR tap leaks!

//RF

yetterben

well i also see today my brake booster is hooked to the side of the intake via a hardline. Right on the drives side of the intake. not the nipple in the back. What the heck is up here. If the booster goes to the hard line in the back what goes to this line on the side. Its a black metal line.

yetterben

well i started it this morning and right away with the surging. I unplugged the map vacume line and pluged it and it stoped....for now. NOw i just need to figure out how to get it out of my burb for testing. This one was loose are they clipped in somehow?

yetterben

Well egr is fine i squeeze it car dies. I moved the map sensor over to my 94 burb which takes the same map and all seems fine. Moved it back to the rs and instant surging. New vacuum hose. Only thing else i could think of is maybe the wireing. It is kinda bent up right at the connector. Or has been moved aroudn to much maybe? idles fine without the hose going to it. Still plugged in though. If i suck on the map sensor port the car dies.

yetterben

well put in a new pigtale. SAme thing map hooked up surge map unhooked steady idle crappy performance over 1/2 throttle. ARGHHHHHH

RFmaster

Man --- I think that you are chasing couple of gremlins. So do me a favor - take as many digital photos (hi-res) as you can (engine compartment, harness, TB, sensors) and stick them on photobucket - put link into the thread. You may need to get a OBD-1 scanner or ALDL cable and WinALDL running on a lappy. To debug your engine management system that has been mindlessly hacked by hillbiliies will need to know what ECM sees and why. Once we know what ECM sees corective action can be surmized. Othersise, it will be a frustrating experience to say the least.

//RF

yetterben

will do i sent you a pm

yetterben

Well tb gasket had no effect. Gonna rent a scanner tonight. what should i be looking for as far what the ecm see's

yetterben

I dont even know if what they have can log info or not. dude is an idiot and has no clue lol.

RFmaster

At idle basic sensor values (Vdc).
Sensor Pin ECM Wire Voltage
CTS B C10 Yellow 1.5 to 1.7 (Depending on coolant temp ~80C)
MAP B C11 LT-Grn 1.5 to 2.0 (20 to 15 in-Hg)
TPS B C13 DK-Blue 0.4 to 0.7 (at idle)
IAT B C12 Tan 1.5 to 2.5 (Depending on inlet air temperature)


1) Verify with a vacuum gauge that you are getting 15 to 20 in-Hg at the

inlet to the MAP sensor.

2)Connect scanner to ALDL connector. In open loop when engine is first started BLM and INT will be locked at 128 counts. Once engine transitions into close loop INT will start tracking O2 sensor voltage. Lean is above 128 counts and rich (ECM is taking out fuel) is below 128 counts.


//RF

yetterben

i will see what i can do about the a scanner. The only other thing i can think of is the intake could be leaking i guess? All the sensors test within spec.

yetterben

took car for a ride around the block what a joke runs like Sh*t. Cant even give it 1/4 throttle

yetterben

WOuld the fuel filter or pump be suspenct in this situation? Man removing that axle does not look like fun.

yetterben

Damn not even 5psi of pressure. Anyone wanna come change it? last time i did a fuel pump i ended up dislocating my knee lol.

yetterben

Here is the log. Also my oil pressure stays at 0 when warm. Dunno if thats a issue or just shitty gauge goes up to 30 above 1,500 rpm's.

Oil is old but full.

Also narrowband o2's have a range from what 0-5v if that is true it is running super lean. Barely ever cracking .180

Lean is above 128 counts and rich (ECM is taking out fuel) is below 128 counts
That statement backwards or what?

RFmaster

O2 varies between 0 to 1 Volt max. Lean is below 450 mV and rich is above 450 mV

RFmaster

Yetterben

She running very lean at 2500-3500 RPM as I have suspected. O2 is below 100 mv and BLM is pushing to 145 counts which is very typical of low fuel pressure. Everything to pointing toward low fuel pressure......

Clear codes - repeat the same test again just to be sure.

Time to drop that tank.

//RF

yetterben

Should i check the voltage at the relay like we discussed. This thing is very weid one day surging the next idle smooth.

yetterben

Rf here is the logs.

First one is when it idled fine.