mechanic1992

So i just rebuilt my 305 and put it back in the car and everything is timed correctly and everything, but when i shift it into reverse or drive the idle drops significantly and will kill the car. what do i need to do to stop this?

Gregvandy

Just went thru this on my 88 Iroc. Need to set the minimum air, then set the tps. There's instructions everywhere. Just search this site. It's easy

mechanic1992

So i made the adjustments and it still is running weird, so i will start my car and it idles at about 600 in park, and it idles fine in park, no problems. now if i shift it into reverse it stays at 600, but when i go to move and then depress the break again and shift it into drive the rpms drop and it dies. Or sometimes the rpms will just drop and itll kill the car when i initially shift it. I think there might be a vacuum leak but i am having a hard time finding it, but also, when i throttle it up, then quickly let off the throttle the rpms will drop all the way and itll also die that way..... any ideas??

rhuarc31

If u think u have a vacuum leak get yourself a propane torch, open it up without lighting it and move it around the hoses and connections and such. I'd make sure your IAC is working correctly as well and all the ports are clear of obstruction.

Street Lethal

iTrader: (16)

Too low, manually raise it to 800-RPM in Park, then set your TPS again. Easier to do it with the engine running. When all is said and done, give the ECM some time to learn....

mechanic1992

So raise it to 800 with the IAC disconnected or with in connected? and what ports are you talking about rhuarc31? But ive done all i can to find any vacuum leak but im not coming up with anything, and i know its not my MAF sensor cause if that wasnt working the engine wouldnt start, i do have a very small exhaust leak on my drivers side because i didnt know that the 92s headers were a fraction smaller in diameter than the 87s, and the O2 sensor is right above that, could the O2 sensor be reading wrong since the leak and be causing it to run like it is? Also, how exactly do i set my TPS? cause i bought a whole new throttle body and accesory kit so its a brand new IAC and TPS but i know it says to rotate the TPS depending on voltage but it doesnt really rotate, unless im just thinking of rotate in a different context or rotating the wrong thing..

Street Lethal

iTrader: (16)

With every sensor connected, remove the block off cap (if it isn't already removed) on the rear side of the throttle body and raise your fast idle speed to 800/850-RPM with a torx screwdriver (T-20). Then, set your TPS voltage accordingly (loosen the sensor, and lower it some until the proper voltage becomes prevalent), then double check your RPM. Repeat the process until you obtain your desired RPM level. Leave the IAC alone....

mechanic1992

I feel kinda stupid, but the block off cap? But it only dies now when it drops RPMS fast, like idle is at 800 and when i shift it into reverse it likes to die but sometimes stays running, but shifting from reverse to drive is fine now, just the big RPM drops is when it likes to die. Id take it to a shop but it wont run long enough

mechanic1992

Just curious, should my plenum have a liquid substance that smells like fuel in it? its all runny and somewhat yellow and black..

Gregs_GSXR

that doesnt sound health

Street Lethal

iTrader: (16)

It sounds like a combination of things, and without the engine right in front of me it is very hard to just point to one area. The block off cap closes off the fast idle screw because it is preset from the factory, but as long as your idle RPM and TPS are both where they need to be, consider your idle set. If the idle drops that low, causing the engine to stall when you shift into reverse, and you are positive that you have no vacuum leaks, then reinspect your fast idle (RPM) and TPS settings. By the way, where is your base timing set? If you were stalling upon deceleration then your IAC would fall into play....

Sounds like a bad sinus infection, try throwing in a few benadryl tablets into the fuel tank, should clear it right up lol. Seriously though, it's more than likely oil being pulled in through your PCV valve on the valve cover. Check your fuel vapor canister's filter while your at it....

mechanic1992

Grr... this is pissing me off... I guess ill look harder for a vacuum leak, but my idle and TPS are set to the best of my knowledge. So is that crap in my plenum a big deal? or is it something i can forget about?

mechanic1992

So i didnt think of it but my buddy told me he thinks my brake boosters diaphragm could be ripped, cause i just noticed when i depress the brake pedal the rpms raise a little, but if i depress and let off, depress and let off a bunch of times constantly my rpms shoot up to about 1000 from the idle 800 in park.... could my booster be bad?

Chevy86 IROC-Z

iTrader: (17)

AAAHHHAAAA. You got a bad Fuel Pressure Regulator. Fuel is leaking into the intake via vacuum line because the diaphram in the F.P.R. is dry rotted. Vacuum is sucking gas into the plenum.

mechanic1992

Thanks Chevy86, i wouldve never thought that. Whats the recommended pressure range on the stock regulator? is 35-70 psi good?

Chevy86 IROC-Z

iTrader: (17)

Yup. You wanna go stock pressure so that sounds around right but keep in mind that normal pressure is approx. 45 lbs at the fuel rail with the Camaro off. You can get an adjustable FPR but only if your PROM chip is programmed with a specific fuel injector (usually higher that 22 lbs). Example, if you have a 22 lbs injector but you install a adjustable FPR, you can actually push more fuel than the injector is designed for, but you can also cause issues with the air/fuel ratio mix. So if you want to go with the adjustable FPR, then you would have to visit the DYNO shop to reprogram the PROM chip.

mechanic1992

****....what if i dont have a dyno shop in town to do that? i live on an island in alaska... is there a way to manually set the pressure?

Chevy86 IROC-Z

iTrader: (17)

Alaska. I just got done watching Deadliest Catch. I feel bad for Jake and Josh. Phil was a great man. He will be missed. Well you can adjust the FPR yourself. Its got a bolt on top of the dome. To increase the pressure, just turn the bolt to plung it deeper inside. This causes the spring to sqeeze which will push the diapham even tighter resulting in a higher pressure inside the fuel rail. This will ultimately result in more fuel being injected into the cylinders. I meant by DYNO shop as in getting the maximun horsepower aswell as fuel economy.

mechanic1992

haha yes alaska, im in juneau. I dont really watch Deadliest Catch ha. So how do i know when the fuel pressure is set just right?

Chevy86 IROC-Z

iTrader: (17)

Here is a good list of pressure readings.
https://www.thirdgen.org/forums/post...17-post13.html

mechanic1992

so 40psi at idle is good? And thanks a lot for the info. just cause im gonna be kinda lazy, do you know the thread size of the schrader valve on the fuel rails off the top of your head? if not ill go look it up ha. and i usually order from summit, and this guage says it only fits 90-93 camaros wth TPI, just curious if itll still work on my 87...http://www.summitracing.com/parts/ACC-74726/ no one in my tiny little island has a fuel pressure gauge! its rediculous

Chevy86 IROC-Z

iTrader: (17)

Your welcome. I dont know bro. Sorry.

mechanic1992

thanks for all the help!

mechanic1992

So i replaced the booster and the FPR but its still doing the same stuff as before, none of the stuff in the plenum but the dying after shifting.... an exhaust leak wouldnt cause it to do that would it? cause the O2 sensor is right above the drivers header which has the small leak, could the sensor be reading wrong or something? anyone have any ideas besides a vacuum leak?

Chevy86 IROC-Z

iTrader: (17)

No. The only side effect of a exaust leak in the engine bay would be the smell of exaust inside the cabin. Did you do a full and proper "TPI Tune up"? If not, here is the links that will help you out with fine tuning the TPI system. If your tach is not reading the correct RPM's, then use a timing light that is equipt with the engine RPM's because you need the actual RPM's so fine tune. So here is the sites that will be usefull for you. It may take care of the issue.
http://webcache.googleusercontent.co...&ct=clnk&gl=us

http://mpikas.blogspot.com/2008/08/t...june-2000.html

rgarcia63

An exhaust leak on the driver side will affect the O2 sensor, usually causing a lean condition, a good size leak will cause the headers to glow cherry red because the ECM will add fuel to compensate for the unmetered air.
FYI - anything thing you do to baseline settings (timing, idle rpm..etc) may push some ECM parameters outside of it's operating range. Example, ECM knows the baseline idle should be 650 @ a coolant of temp of 195 you've got it set at 800, what do you think the ECM will do?

Street Lethal

iTrader: (16)

Setting your idle to 800-RPM w/the TPS and IAC still connected has nothing to do with a baseline setting. There is no reason to disconnect the IAC when setting your idle, so long as your TPS voltage and desired RPM are both where they need to be upon normal startup. If he keeps defaulting to 650-RPM after setting the idle to 800-RPM, then something is obviously tripping the ECM, not necessarily an exhaust leak. Mechanic1992, two questions, one, did you remove your air pump, and two, if you did, did you disable it from the prom?

Chevy86 IROC-Z

iTrader: (17)

Youve been had by Street Lethal.

FYI - The ECM doesnt know what is going on. It's all based on the table of parameters that where programmed into the PROM. FYI - PROM stands for Programmable Read-Only Memory. Which means that the programmed info is non destructable (does not lose memory when power is taken away). So to correct you, the ECM adjusts fuel and timing according to the voltage readings that the various sensors are sending which are then calculated, and adjusted per settings programmed in the PROM to give the vehicle/engine the most fuel economic and power without causing damage to the engine and it's other critical components.

mechanic1992

I did not do a full TPI tune up....

And no i didnt remove my air pump, i put everything that i took off the engine when i did the rebuild right back on it when i put the fresh engine back in.

The only reason i disconnected the IAC was to do that initial tune when you jump the ALDL, turn your car on, wait 30 sec disconnect the IAC. then start engine. that whole process was the only time i disconnected the IAC. And then after starting the car a few times i raised the RPMs to 800 with the idle adjust screw because that was recommended.

rgarcia63

First, it's not a PROM it's an EPROM, a PROM can't be reprogrammed.

Second, this from the manual "Idle speed is speed controlled by the ECM through the Idle Speed Control motor and is not adjustable. The minimum air rate is adjustable as follows."
What that means is that unless you reprogam those parameters to suit your needs the ECM will just pull them back to what is in the EPROM.

Third, programming is mainly for emissions - power and economy will suffer. The ECM has to know what's going on or else emissions won't be met. Yeah, I know who gives a nickel about emissions when there's ways to get around it.

Lastly, if you can't set the baseline idle to specifications you will have other problems because of it.

Apologies, Mechanic1992.

DENN_SHAH

iTrader: (1)

is the motor a stock rebuild?

when you put the motor back in, did you hook up all the ground wires and straps?
is the main battery ground on the block?
is the battery grounded the the body?
is the motor grounded to the body?
are all the grounding points cleaned of paint and rust?
all the grounding wires big enough?

mechanic1992

Yes its a stock rebuild, the only thing different is i put flat tappet lifters in instead of rollers. Everything else was reconditioned or stock replacements. I was on a budget ha. And yes i hooked up all the ground wires and straps, they may not be where they were origionally but they are grounded good. The battery ground is hooted up in the same spot as before the rebuild which was on the smog pump accesory bracket. Pretty much yes to all your questions DENN_SHAH.

As for your post rgarcia63 idk what you are apologizing for, and i am basically an electrical DUNCE, so most of that was somewhat charlie brown adult talk to me.

Street Lethal

iTrader: (16)

That is completely irrelevant, and by the way, idle speed CAN be controlled to whatever you want it to be without even touching the prom. If you pull the IAC out, plug the hole in the throttle body, and leave the terminal connected in the sensor, then set idle speed accordingly once the engine is warmed up, exactly what is the ECM going to do in terms of "idle adjustement"? Move the pintle? So what? It will STAY to where I set it, period. What will moving the pintle do in this case? Nada....

Now, lets get to the root of what is going on here. If your running an automatic, and your scanner is telling you that the ECM is commanding 600-RPM in Park in both Open and Closed Loop, accompanied by that infamous surge at idle, then something is obviously keeping you in bypass, which is why I asked him if he removed his smog pump w/out disabling it. Also note that it won't throw a code when the two air pump connections are disconnected, but it WILL skew the ECM. If his base timing is set correctly, TPS voltage and IAC counts are normal, coolant temp is accurate, no vacuum leaks, then there is no reason why he should be idling that low in Park and/or neutral, unless the owner is failing to detect another problem that he or she might have caused. If not, and the ECM is still commanding 600-RPM in Park, then either the ECM is faulty, or a sensor is not connected, and the ECM is stuck in bypass....

Chevy86 IROC-Z

iTrader: (17)

What!! Do you know what PROM means. Programmable Read-Only Memory. You need some education buddy. You threw yourself under the bus. What do you think the DYNO shops do when they re-program the ECM? You guessed it, they reprogram the PROM because that is where all the instructions are embedded/programmed.. Still dont believe me? follow this link and read and I do mean read before you try to sound smart.....http://www.racepages.com/brand/hypertech.html

Chevy86 IROC-Z

iTrader: (17)

...rgarcia63, you got it handed to you agian .

Chevy86 IROC-Z

iTrader: (17)

.

DENN_SHAH

iTrader: (1)

mechanic1992, sorry for asking this, but you did put the flat tappet lifters on a flat tappet cam, right?

check the air boot between the mass air flow sensor and throttle body. one way to do it is with the motor running at idle in park, lightly pull the boot away from the throttle body. next lightly pull the MAF sensor away from the air boot. there shouldn't be any noticeable change in the idle.
if there is, closely check the boot for any cracks or other damage.
if there wasn't any change, lightly wiggle the MAF sensor connector.
next do a tap test on the MAF sensor.
with a small wrench or screw driver, lightly tap on the MAF. you don't need to smack the sensor, just tap it about as hard as if you dropped a 1/2 wrench 3~4 inches.
if any of those results in a noticeable change in the idle, something isn't right and needs to be repaired.


Chevy86, before you can reprogram a chip, you must first erase it.
for this reason a PROM isn't re-programmable.
EPROMs with a window can usually be reprogramed, but exposing them to UV
light to erase them takes a toll on them as does the programing itself and they can fail at any time.
EEPROMs can normally be erased and programed many times before they fail.

telling someone they have been "had" by another member isn't a good thing.
its a form of trolling, which isn't allowed on this site.
besides, its just bad form.
IIRC, were you not recently on probation for something similar?

mechanic1992

Ha yes i put flat tappet lifters on a flat tappet cam. And i talked to a local chevy god in town and he said it might be that my cat is clogged or collapsed or something and that might be causing it to run like this... any input? Ive got a mechanic making a house run over to my car today to look at it, hopefully he can figure something out, and i will try the MAF tapping thing you just suggested DENN_SHAH

thanks again.

Chevy86 IROC-Z

iTrader: (17)

As a matter a fact, yes I was on probation. But I didnt throw out the first slang term. Trolling? I have no idea what that means. I understand your point though. Thats why I posted a .

Chevy86 IROC-Z

iTrader: (17)

Another way to verify if there is a leak around the intake is to get a propane torch and open up the valve so that the propane gas can escape. BUT do not light the torch!! The idea is to move the torch around any spots that may cause a leak/vacuum leak. If there is a vac. leak, once the propane gets sucked into the intake, there will be a fluctuation in the RPM's. If there is no access to a propane torch, you can use carb cleaner or starter fluid BBBUUUTTTT make sure that there are no stray sparks!!!! This is highly, highly dangerous. You can cause a flash explosion. It is not reccommended, but it can and will expose a leak.

rgarcia63

For what was to come, which did.

You won't be dunce for long if you keep coming here to learn.

Chevy86 IROC-Z

iTrader: (17)

. Even I become a dunce every so often. . rgarcia63, respects 2 you.

Chevy86 IROC-Z

iTrader: (17)

mechanic1992, Whats the situation so far with your Camaro?

John 89 Formula

I don't understand, you replaced a roller cam with a flat tappet cam?

I could be wrong, but aren't the pushrods too short now, or did you replace those too.

mechanic1992

Ok, so despite the fact that i feel like a dumb*** i will share what happened this week. So none of the issues were the real problem, and so i decided to go back to the basics when figuring out why it was running rough, which would be the engine. Now i know it doesnt sound like a V8, didnt have that nice rumble it used to before the rebuild... so i looked further into that, now after several times of shocking myself i came to realize that the entire passenger side(cylinders 2,4,6,8) were not firing at all, and obviously this is a big issue and reason why it would die after shifting, now the reason i didnt see this earlier is cause i figured since all the stuff on the engine was brand new that there wouldnt be any problems with it working, now ive learned my lesson. So either i dont have compression, fuel or spark going to just those four cylinders. I tested spark and i got that to the cylinders, took a spark plug out and i could hear the compression spitting out the spark plug hole. I got called so i had to leave there so i wasnt able to check for fuel... now if im not getting fuel what could be the prob? they are brand new stock replacement injectors and i know they are getting fuel when the system pressurizes.... but what i was thinking was since i did the valve job myself( which it was my first time and i was told you put the piston on TDC and tighten the rocker arms until the point just passed when you have no more up and down play in the pushrods) so i did this to every cylinder. But im thinking that maybe my intake valves arent opening for some reason. But the big question that comes to my mind is... does the drivers side injectors have a seperate ground than the passengers side? Cause if so then maybe i missed or incorrectly grounded the passengers side injectors and therefor those cylinders arent getting fuel. Cause im sure im getting commpression cause my pistons have brand new rings, but also my exhaust valves could be stuck open a bit causing a lack of compression. So what i am going to do next is borrow a compression tester from a buddy and compare the drivers side compression to the passengers side and see if compression is the issue, cause to make sure i had spark i swapped the drivers side spark plugs and wires over to the passengers and passengers to drivers and the drivers was still firing so i know that all my ignition stuff is good, but like i said the one thing i havent fully tested yet is fuel.

mechanic1992

But yes John 89 Formula i did replace the pushrods with longer ones to account for the shortened lifters

vetteoz

iTrader: (13)

How did you miss that; should have sounded like sh**

Two seperate injector circuits ; one for each bank.
12V to injector , injectors controlled by going to ground at the ECM

Have you checked the injector fuses?
Do you have 12V on one side of the injector plugs ( pink / blk wire ? ) in the bad bank?
Is the other terminal of injector plug open circuit ; as in not to ground ?

rgarcia63

Don't try to measure for continuity to ground at the ECM. Use a Noid light - plug it into any injector connector on that side, if it flashes when cranking the ECM is driving the 12v to ground as it should.
If there's not a wiring problem, and it doesn't flash then the ECM injector driver for that bank maybe faulty, but be sure to check the 10amp fuse for that bank first.

DENN_SHAH

iTrader: (1)

X3 on the fuse or wiring for the bank not firing.

i believe the 165 ECM is just like the 7730, a wire for each bank to the ECM, but there is only one injector driver in the ECM to fire both injector banks.

rgarcia63

I'm sure it's a batch fire which means that each bank is fired separately in intervals left right left right, (bank one bank two,) so on and so forth.
Although the diagram shows one solid state switching circuit to ground, batch fire can't work with only one driver for both banks, unless there's a solid state switch (which is what a driver is) to enable one bank and disable the other.

I been wrong many times, if I'm wrong it won't be the last time.