When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
yes I do and I think he change it. I wonder if he still has the old one?
i will find this module and see if i can get a part number on it. that said, i want to scan the car this evening and see if i can get ks readings (and 02) to see if they are elevated at idle. car runs like a bat out of he77 everywhere other than the stalling while backing into a parkinglot and the stumble/bog/hesitation when stabbing the throttle.
checked, and i have the 16022621 ORIGINAL esc unit on my 85.
tonight when i get the car running i will see if tunerpro rt v5 will see knock counts.
from what i read though guys, the esc upgrade seems to solve false knocks and retardation at high rpm. my issue is low rpm at idle.
thanks for bringing that thread to my attention Aklim. Good to know and I'll see if I can get the part affordibly and see if it makes a difference down the road.
checked, and i have the 16022621 ORIGINAL esc unit on my 85.
tonight when i get the car running i will see if tunerpro rt v5 will see knock counts.
from what i read though guys, the esc upgrade seems to solve false knocks and retardation at high rpm. my issue is low rpm at idle.
thanks for bringing that thread to my attention Aklim. Good to know and I'll see if I can get the part affordibly and see if it makes a difference down the road.
Easy there, Hoss. Lets see the O2 sensor readings first. Some have said they are good for 100K, give or take or if you send exhaust crap down the line, whichever comes first. That is part of the reason I don't put snake oils in my gas. You probably will get knocking when you goose the throttle. I know I do.
I'm not convinced that it has O2 sensor written all over it. Lets start with basics.
You checked fuel pressure yet? With the hose off and running? Does it hold pressure after shutdown? What about at WOT? Is the pump supplying enough at WOT or just at idle?
Next thing is spark. IIRC, you changed the plugs, wires, cap and rotor and verified you had good spark.
Refresh my memory. Did you try to reset IAC any more? You said you got 30 counts at the throttle screw all the way out. 20 to 30 is fine. So if you have 30 counts with everything but the engine off and at operating temp, try turning the screw in till it contacts the throttle lever, rev and see what it is after it settles down.
Easy there, Hoss. Lets see the O2 sensor readings first. Some have said they are good for 100K, give or take or if you send exhaust crap down the line, whichever comes first. That is part of the reason I don't put snake oils in my gas. You probably will get knocking when you goose the throttle. I know I do.
I'm not convinced that it has O2 sensor written all over it. Lets start with basics.
You checked fuel pressure yet? With the hose off and running? Does it hold pressure after shutdown? What about at WOT? Is the pump supplying enough at WOT or just at idle?
Next thing is spark. IIRC, you changed the plugs, wires, cap and rotor and verified you had good spark.
Refresh my memory. Did you try to reset IAC any more? You said you got 30 counts at the throttle screw all the way out. 20 to 30 is fine. So if you have 30 counts with everything but the engine off and at operating temp, try turning the screw in till it contacts the throttle lever, rev and see what it is after it settles down.
so, as you know i put brand new plugs and wires in this car 2 days ago. ive started it 5 times for a couple minutes each time to video the flywheel (different issue, dont ask).
saw the oil slick in the above post with the condensation rust spots, and thought hey, why not pull the plugs. i pulled 4 and 6 and they have oil on them.
so, if compression was good, which it was, then, do i have toasted valve stem seals? i do get a nasty puff of oil smoke on startup. if valve stem seals are bad, would that have any impact on runability? like would that impact rough idle?
well, it was pretty clear from the oil on the plugs, the oil residue in my exhaust, and the puff of smoke when i first startup, that my valve seals are toasted. (checked pcv and valve was working fine)
So, i took a slight detour from diagnosing my crappy idle to replace the valve seals because afterall i did just get a brand new set of plugs and i dont want to foul them too!
question:
what condition causes the pushrods to have black carbon buildup on them? it rubs off with my finger.
pic:
one side had this gasket. the other side had red rtv. im going with felpro. <br/><br/>check out the black carbon on the pushrods.
Last edited by VikingTrad3r; 11-28-2015 at 02:05 AM.
I'd just do the seals and roll the rods on the flattest surface you know. They better be rolling true or you toss the lot of them. Try not to worry too much. It isn't your car originally so the best you can do is make sure they are equal length and rolling perfectly flat. One wobble and you toss all 16.
I'd just do the seals and roll the rods on the flattest surface you know. They better be rolling true or you toss the lot of them. Try not to worry too much. It isn't your car originally so the best you can do is make sure they are equal length and rolling perfectly flat. One wobble and you toss all 16.
With the oil your getting on your plugs.....I would be looking at compromised intake gasket. I think your sucking oil from the valley into the intake and fouling the plugs. In one of your earlier posts here, you mentioned that a torx bolt was loose. IF there were several on the intake that had backed off then the intake gasket is not tight against the head/intake. I don't think you would get that much oil on the plugs with a bad valve seal.
With the oil your getting on your plugs.....I would be looking at compromised intake gasket. I think your sucking oil from the valley into the intake and fouling the plugs. In one of your earlier posts here, you mentioned that a torx bolt was loose. IF there were several on the intake that had backed off then the intake gasket is not tight against the head/intake. I don't think you would get that much oil on the plugs with a bad valve seal.
If that theory is right, closing off the butterflies and relying on the IAC (metered air leak), how is he getting 30 counts which tells me that the ECM wants more air? Usually when I have a gasket failure or something that introduced unmetered air, the IAC is 0.
If that theory is right, closing off the butterflies and relying on the IAC (metered air leak), how is he getting 30 counts which tells me that the ECM wants more air? Usually when I have a gasket failure or something that introduced unmetered air, the IAC is 0.
Aklim is correct about the iac counts with the throttle blades closed.
I get 30-50 with it settling at 40 most of the time. so fairly tight after fixing a huge vac leak i had. shouldn't be any extra air getting in.
we are in the process of doing the valve stem seals. i found ONE pushrod bent ever so slightly on the intake valve. like, really really barely bent.
I can see that the previous owner was into this car in multiple places. I have placed an ad for a replacement rod. No, I am not tearing down the engine and i was tempted to just put the rod back in and keep going but im not going to do that.
its a very long shot I think, but then again, I don't understand too much about this. I asked JoeC who had an issue with his 85 waaay back in 2008 who had an issue with running rich and bogging like mine, and his issue turned out to be a valve that was adjusted too tight. Perhaps, perhaps.....the PO adjusted these too tight on the one cylinder then it bent slightly and then the valve wouldn't open all the way on the intake side which should technically make the car run rich in that cyl right?
anyway, i will replace the pushrod, proceed with the valve seals, and see what happens.
Thanks all for your continued input in our quest to get our beautiful 85 z51 running like it came from the factory.
VikingTrad3r.
PS. it is quite amazing how messed up a car can get from previous owners and their hack job repairs. just ***** nilly "keep it running" type stuff. For the amazing cars that are the c4 corvettes, it appalls me to see how neglected they get@!!!!!
I get 30-50 with it settling at 40 most of the time. so fairly tight after fixing a huge vac leak i had. shouldn't be any extra air getting in.
I can see that the previous owner was into this car in multiple places. I have placed an ad for a replacement rod. No, I am not tearing down the engine and i was tempted to just put the rod back in and keep going but im not going to do that.
its a very long shot I think, but then again, I don't understand too much about this. I asked JoeC who had an issue with his 85 waaay back in 2008 who had an issue with running rich and bogging like mine, and his issue turned out to be a valve that was adjusted too tight. Perhaps, perhaps.....the PO adjusted these too tight on the one cylinder then it bent slightly and then the valve wouldn't open all the way on the intake side which should technically make the car run rich in that cyl right?
PS. it is quite amazing how messed up a car can get from previous owners and their hack job repairs. just ***** nilly "keep it running" type stuff. For the amazing cars that are the c4 corvettes, it appalls me to see how neglected they get@!!!!!
I wouldn't go lower than 20 so if your screw touches the throttle plates and even moves it open a little, it would give the ECM even more room to adjust so go ahead and set for 20 since your screw is not touching the lever.
I don't know much about engine design but I'd find it hard to think that one slightly bent pushrod will cause an entire engine to run as rich as you describe.
Don't know. Why bother? Check with Jegs but if that part is what I think it is, why speculate for $41?
Check what the O2 sensor says. If there are enough miles or the sensor is old and it makes you feel good, replace it. I just had a front O2 sensor on a W140 car that supposedly went bad. Rear was just fine. Kept throwing a P0133 code indicating it was the front. Changed the rear and all is well with the world.
Your's wasn't as bad as mine. Starter relay, among many other things failed and fused. Instead of changing the relay and perhaps the socket, he decided to install an "Anti Theft device". You put the key on run and have a push button to crank. Talk about Ghetto McGyver fixes.
so im going through my merry way listening to christmas music while replacing my valve stem seals, and i get to cyl 7. put the 90 psi into the cylinder 7, it pushes the piston down, and then I start to hear the overflow tank of the cooling system start to bubble.
give it to me straight. what does this mean. am i pulling the heads and doing a head gasket or is it possible that this is an intake gasket?
cyl 7 was one of the my cyl's with the fouled oil plug.
compression was 158-161 with no leak down on all cyls.
what gives? if i pressurize the cylinder, is there any way to get that pressurized air into the cooling system through the intake gasket?
i kinda don't think so.
i await your responses.
VikingTrad3r
Last edited by VikingTrad3r; 12-02-2015 at 01:35 AM.
Applying air to any cylinder at any time and causing air to come out the over flow tank = bad news. Somethings letting air into the water jacket.
As to whats doing that it can vary.
1. Blown head gasket. (most likely)
2. Cracked heads.
3. Cracked block.
4. (Nearly impossible but who knows) Blown intake gasket. It would be very hard to enough air to make it over from the intake to override the radiator cap but it could in theory happen but VERY UNLIKELY.
method for narrowing down the gasket vs the block?
My compression test checked out fine....
so, I am a bit concerned that i have a cracked block vs a blown head gasket. thinking if my piston happend to end up at top dead center, or above the leak anyway, maybe that is why my compression was good.
if the piston is at bottom dead center, which is where it would have been with me putting pressure into the cyl, and you get the leakdown....
but if you use a breaker bar to hold the cyl at top or even mid stroke and there is no leak down, can i slowly let the pistion down using the breaker bar and use this as a way to dial in weather or not this is a head, head gasket, or block that has been blown?
Originally Posted by crowz
Applying air to any cylinder at any time and causing air to come out the over flow tank = bad news. Somethings letting air into the water jacket.
As to whats doing that it can vary.
1. Blown head gasket. (most likely)
2. Cracked heads.
3. Cracked block.
4. (Nearly impossible but who knows) Blown intake gasket. It would be very hard to enough air to make it over from the intake to override the radiator cap but it could in theory happen but VERY UNLIKELY.
Last edited by VikingTrad3r; 12-02-2015 at 12:54 PM.
Where the piston is isn't going to change the fact you have air going into your water jacket.
If air comes out the overflow tank only on that one cylinder then the head gasket is blown between that cylinder and a water passage or the heads cracked at that cylinder.
Air coming out the radiator overflow when shot into a cylinder requires head removal. At least you know which head it is
Well that sure sucks. Sorry to hear. At least you know now and have a direction to go.
exactly, and that is why im ok with it. im a business builder and u have to deal in truth with the faith in your ability to get it right.
this is my first time working on a car and ive come along way in a short time with the help of people here!
should take me a couple weeks to get it done.
the irony about all of this, is that ive had all the accessories off the front. had the intake off. this was all before i knew enough to start evaluations at the base of the foundation, meaning compression and internal engine cooling. ive even had the cooling system drained and flushed! ive done all the work leading right up to undoing the head bolts!
hopefully if another noob comes along this thread can help them out:
before you do a single diagnostic repair, even something as easy and benign as an iac, and even if your symptom is a "crap idle" as i so eloquently out it, ESTABLISH THAT YOUR ENGINE GASKETS ARE NOT COMPRIMISED ON THE OIL AND COOLING SIDE.
as long as that is good, then u can fix and replace the smaller insignificant items.
course, i probably read that somewhere a year ago, and just glazed over it as a noob didnt pay any attention to it. ive spent hundreds of hours kearning how to diagnose the small (they appear insignificant and easy now) and all for naught if you have a blown head/intake gasket and/or a cracked block!!
ill continue the process and hopefully with help here ill see this through and have the 85 running like it should.
11-25-2015, 04:05 PM
