no way will my car go closed loop
Thread Starter
7th Gear
Joined: Jul 2002
Posts: 7
Likes: 0
From: Yellowknife N.W.T
no way will my car go closed loop
Hi all. 3 months ago I completed my rebuild of my 86. My problem is, I won't go closed loop. Also the car won't stay running without keeping the gas on because it will want to idle below 600 rpm. Sometimes if I cycle the key a couple times, it will idle up at 8 or 9 hundred until it warms up. I have tried 2 o2 sensors, heated o2 sensors, my own ground for the 02 sensor, checked ecm grounds, new ecm, and the stock chip. There's no codes. But the block learn says 15. I know that the car shouldn't even run that rich. It definately is running very rich and puffs black when stepping on it. Fuel pressure is good. I called Ed Wright but he would not even talk with me. Just said my O2 sensor wasn't getting hot enough. My sensor is on the #7 tube on my header. When I read the O2 reading, it's toggling up and down like it's supposed to. The only thing different from some of the combinations I see on here is my camshaft. It has 110 degrees lobe seperation. I don't think this is it. It really feels like a programming problem to me. There are a couple other things I've checked but can't think of them right now. Throw some idea's at me please. I'm finally at a dead end. Keep this thread alive pleeaassee.
Thread Starter
7th Gear
Joined: Jul 2002
Posts: 7
Likes: 0
From: Yellowknife N.W.T
Re: no way will my car go closed loop (86 4+3)
I'm sorry my mods don't show for some reason. I have a 52mm throttle body, edelbrock intake, adjustable fuel reg, 12-234-2 comp cam, ceramic hooker headers, flowmaster exhaust, .030 over, keith black flat tops, Ed Wright chip.
Drifting
Joined: Mar 2001
Posts: 1,636
Likes: 3
From: Lafayette IN
Re: no way will my car go closed loop (86 4+3)
Fisrt, your LSA of 110 isn't helping things out much. Besides that point, the cam of 212/218, 0.447/0.454 really isn't too radical for TPI.
I think that with a scanner, your O2 voltage is going to be high...in the 820-850 mV range....and that it is going to stay there. If you got one of the non-custom chips from Ed, there within lies the problem. It is not modded enough for cam changes. That cam makes your engine less volumetrically efficient at low RPMs in exchange for better breathing at high RPMs. You will be rich at the bottom end and if the ECM can't compensate enough, then it just can't. Plus, it can't compensate if you don't go into closed loop as you already know.
If you ask me, I would tell you to lower your fuel pressure. Excess fuel *can* keep the O2 too cool.
And I take it you are noticing that the ECM doesn't go closed loop with a scanner?
Good luck. -Matt-
I think that with a scanner, your O2 voltage is going to be high...in the 820-850 mV range....and that it is going to stay there. If you got one of the non-custom chips from Ed, there within lies the problem. It is not modded enough for cam changes. That cam makes your engine less volumetrically efficient at low RPMs in exchange for better breathing at high RPMs. You will be rich at the bottom end and if the ECM can't compensate enough, then it just can't. Plus, it can't compensate if you don't go into closed loop as you already know.
If you ask me, I would tell you to lower your fuel pressure. Excess fuel *can* keep the O2 too cool.
And I take it you are noticing that the ECM doesn't go closed loop with a scanner?
Good luck. -Matt-
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: no way will my car go closed loop (86 4+3)
So if your O2 sensor is toggling correctly check coolant temp with the scanner. Either being off will keep you out of closed loop.
For the idle problem first check for any vacuum leaks, dirty TB planes/bore and clean/replace the IAC.
See if you can get a test MAF, when mine died it threw no codes but caused some real starnge idle problems.
For the idle problem first check for any vacuum leaks, dirty TB planes/bore and clean/replace the IAC.
See if you can get a test MAF, when mine died it threw no codes but caused some real starnge idle problems.
Drifting
Joined: Mar 2001
Posts: 1,636
Likes: 3
From: Lafayette IN
Re: no way will my car go closed loop (65Z01)
So if your O2 sensor is toggling correctly check coolant temp with the scanner. Either being off will keep you out of closed loop.
I Missed that part. I saw using different O2s and figured it wasn't toggling. I would have to agree coolant temp that the ECM is seeing is a prime culprit. Doh.
Thread Starter
7th Gear
Joined: Jul 2002
Posts: 7
Likes: 0
From: Yellowknife N.W.T
Re: no way will my car go closed loop (HighHopes85)
Thanks guys, I'll adjust my fuel press. tomorrow. My coolant temp is not the culprit. I purposely removed the fan fuse and let it get good and hot to make sure that wasn't the reason.
Melting Slicks
Joined: Apr 2001
Posts: 2,121
Likes: 223
From: Ca.
Re: no way will my car go closed loop (86 4+3)
Thanks guys, I'll adjust my fuel press. tomorrow. My coolant temp is not the culprit. I purposely removed the fan fuse and let it get good and hot to make sure that wasn't the reason.
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Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: no way will my car go closed loop (86 4+3)
Can you go back to the original chip. Sounds to me that something is hosed up in the chip. Try the original and see if it goes to closed loop.
Also if you rev it up to say 2300 and hold it there after startups, does it go to closed loop?
Like stated before if it does it at say 2300 then your o2 sensor is probably not getting hot enough.
Also there is a time delay set in the chip sometimes too. That is why I would try the original and see if that helps.
Also if you rev it up to say 2300 and hold it there after startups, does it go to closed loop?
Like stated before if it does it at say 2300 then your o2 sensor is probably not getting hot enough.
Also there is a time delay set in the chip sometimes too. That is why I would try the original and see if that helps.
Thread Starter
7th Gear
Joined: Jul 2002
Posts: 7
Likes: 0
From: Yellowknife N.W.T
Re: no way will my car go closed loop (ski_dwn_it)
I tried the stock chip. No change. I also tried revving it up for a long time. No change. I performed the O2 test on the tech 1 and it wouldn't complete because it wouldn't go closed loop. I still think it has something to do with programming as well as the block learn reading 15. As mentioned before, I will lower fuel pressure tonight after work. I was thinking a possible leaking injector on #7 but that seems quite coincidental since it wasn't doing it before my project. As well as being on the same cylinder as the o2. Keep the ideas coming and I will keep you posted.
Burning Brakes
Joined: Oct 2001
Posts: 1,033
Likes: 0
From: Tracy California
St. Jude Donor '05
Re: no way will my car go closed loop (86 4+3)
I remeber a while back talking to a Tuner, and they rattled off the condidtions that must be met before you can go closed loop. Hmmm now only if I can remember what they were.
The 110 LSA isn't the problem. I run a big nasty cam on a 110 LSA without any problems. My car idles fine and has never stalled. Hopfully someone will chime in with the conditions.
KM
The 110 LSA isn't the problem. I run a big nasty cam on a 110 LSA without any problems. My car idles fine and has never stalled. Hopfully someone will chime in with the conditions.
KM
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: no way will my car go closed loop (88-406)
I will tell you this.
Almost everything is based on the MAF coming into the engine. LV8 is calculated from it just to mention one.
If the sensor is not reading the correct amount of airflow, all sorts of weird things can occur. I have never heard of no closed loop, but it might have an effect.
Can you get a different one from someone else or better yet to make sure its not a relay or something, put your MAF in there car and see if it goes to closed.
If you can find someone will. You could swap out a bunch of stuff and try it in their car until you have either eliminated everything, or have pulled your hair out.
Man I wish I could help you more. SOund like it the MAF because it should not be stuck in cell 15 all the time. I will find out what governs the cells. I think its the MAF though. I will make sure.
Jesse
Almost everything is based on the MAF coming into the engine. LV8 is calculated from it just to mention one.
If the sensor is not reading the correct amount of airflow, all sorts of weird things can occur. I have never heard of no closed loop, but it might have an effect.
Can you get a different one from someone else or better yet to make sure its not a relay or something, put your MAF in there car and see if it goes to closed.
If you can find someone will. You could swap out a bunch of stuff and try it in their car until you have either eliminated everything, or have pulled your hair out.
Man I wish I could help you more. SOund like it the MAF because it should not be stuck in cell 15 all the time. I will find out what governs the cells. I think its the MAF though. I will make sure.
Jesse
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: no way will my car go closed loop (88-406)
Ref: "How to Tune & Modify Chevy Fuel Injection", by Ben Watson: three things are required for the ECM to enter closed loop mode after startup:
1) the coolant temp must reach a certain temp
2) the O2 sensor must reach operating temp
3) a preset time must have elapsed
So, the ECM is seeing a problem in one of those areas or the ECM is faulty.
1) the coolant temp must reach a certain temp
2) the O2 sensor must reach operating temp
3) a preset time must have elapsed
So, the ECM is seeing a problem in one of those areas or the ECM is faulty.
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: no way will my car go closed loop (65Z01)
Hey there.
I just thought of something after I hit the send button.
You may have tried this, but I did not recall reading it anywhere in the posts. I was just scanning through the other suggestions, and don't remember seeing it.
Try this:
Disconnect the battery for 1 or 2 minutes. Reconnect and see if all is well then. Good luck.
You may have already did this, but its worth a try.
I just thought of something after I hit the send button.
You may have tried this, but I did not recall reading it anywhere in the posts. I was just scanning through the other suggestions, and don't remember seeing it.
Try this:
Disconnect the battery for 1 or 2 minutes. Reconnect and see if all is well then. Good luck.
You may have already did this, but its worth a try.
Instructor
Joined: Jun 2000
Posts: 184
Likes: 0
From: Marysville, WA
Re: no way will my car go closed loop (86 4+3)
Your cam has a 110 degree lode seperation which is a KILLER with computer controlled cars. A custom chip is a must. Your overlap in your cam is probably giving the computer fits at idle. I suggset talking to a chip guru to see if the rich condition can be programmed a out. Good luck with your vette. It sounds devilishly fast!!
Burning Brakes
Joined: Oct 2001
Posts: 1,033
Likes: 0
From: Tracy California
St. Jude Donor '05
Re: no way will my car go closed loop (86 4+3)
Hey 86 4+3
Did you degree your cam? I'm beginning to wonder if you've got all that stuff taken care of.
You should be running a custom prom! But I can gaurantee you that the cam you have is very very mild. I would expect it to idle very very nicely. I've run the XE268 and the XE288. The 288 is radical but the 268 was silky smooth. Your cam is almost the smallest Comp makes.
KM
Did you degree your cam? I'm beginning to wonder if you've got all that stuff taken care of.
You should be running a custom prom! But I can gaurantee you that the cam you have is very very mild. I would expect it to idle very very nicely. I've run the XE268 and the XE288. The 288 is radical but the 268 was silky smooth. Your cam is almost the smallest Comp makes.
KM
Thread Starter
7th Gear
Joined: Jul 2002
Posts: 7
Likes: 0
From: Yellowknife N.W.T
Re: no way will my car go closed loop (88-406)
yes my cam is degreed. I lowered my fuel pressure to 35 pounds. I couldn't lower it any more due to the adjusting screw backs up into the bottom of the plenum. Same problem. The block learn even sat at 2 for one key cycle. I had my battery disconnected several times allready. I don't think that will clear anything. When I ordered a prom through Wright, I gave him all my information about my build up. Including my cam specs. But I still would not be surprised if this is my problem. Does the chip provide the tables to read from in open loop as well as closed loop? I used my little blue point thermal laser gun on the outside of my ceramic headers and was only getting 375 to 425 degrees. I'm sure the inside will be hotter but how much? The O2 sensor needs 600 to 650 degrees if I remember correctly. My maf reading was right around 9 at idle. Which I think is right. There's not many other c4's where I live so part swapping is tough. Keep the ideas coming. If there's someone willing to talk me through everything I need to know about burning my own chip, then I'll order everything and get started.
