ESC Symptoms

[RareGMFan]

I mentioned in a different thread that now my TGP is knocking on occassion. Been driving it several weeks, and other then literally one time, never heard it before the last few days. I have a 25 minute or so drive to work. When I start her up, it starts REALLY hard (and any time it's been sitting for a while). Takes 2-3 tries of cranking for 4-5 seconds. When she turns over, everything sounds ok (except for the high idle, but that, and the hard start, are different TPS related issues, I think). I drive it for about 10 minutes before the high pitched metallic sound becomes quite evident and loud. I don't hear it so much while I'm just cruising along, but when I come to a red light, I can clearly hear it bounching off the cars next to me, which is quite embarrassing. :oops: Anyways, natrually by this point, I'm freaking out about it thinking "oh crap, there goes my motor". But.....as I get closer to work, I'll notice the sound dying down a bit, so that by the time I pull in to my work place, it's dead silent again, just like at start up. :shock: So that gave me some relief and hope that it isn't a rod or something. Same thing happens on the way home, too.

 

Well, I've been digging through the TGP Service Manual, looking for as much info as I can gather for the TPS issue, and I stumbled upon another code I retrived, but forgot all about: CODE 43: ESC Circuit. I suspected a fault in this circuit could lead to what I'm hearing, and sure enough, the "symptoms" section showed ESC as a possibility when hearing "a mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening. Sounds like popcorn popping".

 

So then, I was wondering if anyone else has ever dealt with this issue, and has found changing the sensor, or finding the short, which ever applies, to have solved the problem.

[5speedz34]

Well, I had the same code on my first Z34. It sounds like you're getting spark knock, and the car is retarding the timing by the time you get to work.

 

Does it seem to get slower after you warm it up?

 

IMO You either have something wrong with your plugs or wires, but I would check the knock sensor first. It's located on the firewall side of the block above the tranny.

[RareGMFan]

Well....the bizarreness continues. I spent most of the day cleaning up my apartment today, so I didn't have too much time to mess around with the car. But I did go out to look at a few things. Started her up (did its usual very difficult to start thing), and the idle wasn't really too high this time. I unplugged the IAC, which caused a very quick, minor surge in idle, and then it went right back to where it was, so I don't think that's an issue. Then I went to take off the TPS harness. I couldn't tell if the idle started to get erratic on its own, or if me touching the TPS wiring was causing this. Hard to say. But when I unplugged it, the idle dropped a bit. Plugging it back in didn't seem to make a difference, though. I revved the throttle after that, and it COMPLETELY cut out, and shut the car off 2 times in a row. On the third try, I let go a little sooner when it cut out, and as soon as I let go, the engine went right back to firing away. I shut her down after this.

 

Next, I pulled the computer out of its spot to see if I could find any obvious wiring damage to any of the harness. I also pulled the mini harness in that area for a brief look. Nothing suspicious. I then pulled the front plug to make sure the gap wasn't too horrible. It was actually still gapping at exactly .045, much to my surprise. I put that back, and reinstalled the plug wire.

 

I started her up again to see if I could hear any knocking. The EXTREMELY faint pinging was still there (nothing out of the ordinary that I don't hear an many GMs). What surprised me though was.....it was idling perfectly. :shock: No surges, and nice and low RPMs. I waited for a few minutes to see if it would go nuts again. Nothing. So I got in, and took it around the block a few times. It was driving just as smooth as when I first got her running. I pulled into the back of a strip mall, and drove close against the wall there to see if I could hear any knocking. Nothing. So after 10 minutes of driving it around, I parked again, still running. My dad stopped by, and I commented that it wasn't making the sound anymore, and actually regained some power and smoothness. So we took it out again for a spin (haven't shut it down, yet). I pushed it fairly hard on a straight away behind my apartments, and it actually hauled some ass, and chirped into 2nd. :shock: I came around to the strip mall in front of my apartments again, and listened closely against the wall. Still nothing. So I parked it yet again, let it run for a few more minutes, then shut her off. It was running for around 25-30 minutes (equal to a trip to/from work), and everything was functioning fine.

 

Earlier tonight, I drove it to a friend's house (about 10 minute drive), and still smooth and powerful, with good idle. Leaving his house, it sounded good. Had the stereo up a bit, so I'm not sure at what point this started, but I stopped at a gas station just a bit passed my apt. to grab a drink, and when I pulled in, I noticed it was tapping again. Needless to say, I was disappointed. When I got back in the car and started it again, it was there still, but shortly after leaving the gas station, it was gone again, and never came back during the 2 or 3 minute trip home. Man......what GIVES with these cars?? I'm just glad it's nothing as serious as a rod knock. I would assume that that wouldn't really go away ever, let alone after 30 minutes of non-stop operation. Need to do some more probing tomorrow (will most likely just buy a new CS, and swap it). Oh.....and to top things off, I my harddrive is taking a dump on me. Rebooted itself 4 times this morning, and is making horrible noises. Luckily, I squeezed this post out. Man....when it rains, it pours.

[DaveFromColorado]

what you're probably hearing is spark knock, or detonation due to a bad plug, or plug wire and it's trippin' the hell out of the knock sensor and it can't pull the timing any further back (IE: the Electronic Spark Control error) you could also have a failing injector not delivering enough fuel to one cylinder, causing that one to knock - or even better yet, you could have a bad lifter causing knock tripping the knock sensor - or even some sound from your transmission causing a knock that's heard by the knock sensor causing the ESC problem.

 

I'd start by inspecting the plugs and wires, and maybe even replacing them (Depending on age) if they are fairly new, they should be under warranty and you can just replace 'em, I'd probably just replace the plugs too while I was in there.

 

Good luck.

 

--Dave.

[5speedz34]

what you're probably hearing is spark knock, or detonation due to a bad plug, or plug wire and it's trippin' the hell out of the knock sensor and it can't pull the timing any further back (IE: the Electronic Spark Control error) you could also have a failing injector not delivering enough fuel to one cylinder, causing that one to knock - or even better yet, you could have a bad lifter causing knock tripping the knock sensor - or even some sound from your transmission causing a knock that's heard by the knock sensor causing the ESC problem.

 

I'd start by inspecting the plugs and wires, and maybe even replacing them (Depending on age) if they are fairly new, they should be under warranty and you can just replace 'em, I'd probably just replace the plugs too while I was in there.

 

Good luck.

 

--Dave.

Dave, if it was a lifter or something in his trans don't you think he would be able to hear it if it was audible enough for the knock sensor to hear it?

[RareGMFan]

Dave, if it was a lifter or something in his trans don't you think he would be able to hear it if it was audible enough for the knock sensor to hear it?

 

Well, like I said, it's been plenty audible on my drives to and from work, last week. Only yesterday, everything seemed to settle down, and I didn't really hear it during that 30 minutes, or so. It does very much sound like a lifter/valve, something to that effect, which I'm most afraid of it being, but we'll see. I know the wires are crap. I replaced the front three a while back just because they were easy to get to, and one of the front three LITERALLY had a boot ripped in half at the spark plug. That's why I couldn't believe it ran as good as it did the first time we got her to fire up. I have a set of Taylor 8 mm wires going on, and NGK Iridium plugs, so I'm not worried about the junk plugs and wires on there right now. I also have a brand new set of Delco coils and ICM to go on. I've already had the fuel pump, filter, and sending unit replaced, and had the tank and injectors cleaned out. Almost all fuel related things (besides the FPR, which I have a new one of ready to go, as well) have been taken care of, unless of course, one of the injectors is completely done.

 

I'm also wondering about the oil pressure. The gauge shows it being fairly low when it gets really warmed up, but still above red (at least 10 psi). What I'm worried about is that the gauge occassionally drops to nothing. At first, I thought the sending unit was fried, but then I noticed it ONLY does it on left turns. :shock: Jeff M gave an explaination of what this might be. I don't know if it's related to the noise, though, because when there's NO noise, it doesn't matter whether it drops to 0 or not. When there IS noise, it doesn't matter if the pressure is high, or at 0.

 

I wanted to take a closer look at this thing today, but it's over 100° right now. :shock: Plus I gotta' get my new hard drive installed and formatted, and all that good stuff that accompanies starting all over with your computer. :x

[5speedz34]

I would change your plugs and wires, and then go from there.

 

Why would a lifter or valve tick louder after it warms up though? On the 3.4's the lifter tick goes away after the car warms up, I would assume the 3.1 would be the same.

 

About oil pressure, thats just wierd as shit. Maybe when you make a left the pump isn't getting enough oil?

 

I'm still sticking to the knock sensor/ignition system.

 

Good luck.

[DaveFromColorado]

with a lot of the pushrod engines, the tick's from lifters can get louder because the oil pressure usually drops with tempature. I'm still guessing it's bad plugs/wires - the other stuff I mentioned was just crazy stuff I've seen make these cars do crazy stuff - or at least things to look at.

 

Left turns and evacuating the oil pump pick up - yeah, been there - usually that SHORT ammount of time isn't enough to dammage anything, just don't hold the wheel to the left and see how long it'll run.

 

these engines can run on as low as 15 psi at 1100 RPM's - a lil' lower with lower engine speeds - also you want to see about 10 psi per 1000 RPM's till about 60 (I think 60 psi)

 

let us know how it's runnin' after you change the plugs/wires/coils/ICM

 

--Dave.

[RareGMFan]

Why would a lifter or valve tick louder after it warms up though?

 

with a lot of the pushrod engines, the tick's from lifters can get louder because the oil pressure usually drops with tempature.

 

 

Precisely why I'm a little worried/nervous, yet. I'm afraid it isn't getting enough oil at times. Tony, mine goes away, too, on initial start up. There's ticking for about 5 seconds (on just about every car I have), and then, it's like the oil swallows it up, and it's silent after that. That's why I'm afraid the engine may be getting starved for oil when this noise happens, though like I said, it also goes away by itself by the time I make it to work, too.

 

Update on some driving yesterday. Went to eat with a friend. It was literally 102° out, so I said we'll take my car just to see what happens (since it was running nicely the day before). Well, the idle is right back to ridiculous again, but it still didn't make a sound during the 10 minute drive to the restaurant, inspite of the heat, and some hard pushes along the way. BUT, on the way home (were at the restaurant maybe 45 minutes), it started out silent again, but got REALLY noisy by the time I got home. This is getting real annoying, real fast. Well, as was mentioned, I'll do the complete tune-up first, and go from there.

 

Dave - Can't the entire oil pick up be replaced? I'm thinking about doing that, as well as an oil pump to try and rule out the pressure part. When it gets warmed up, it's not seeing jack for pressure. Doesn't matter how hard I accelerate, or how fast I go, it hovers just below 40 psi at its most. This is whether there's noise, or not.

 

I'll update the rest on this next weekend.