I put on a set of hedman smog shorties, a set of acell 8 mm universal radio supresion wires and a set of the made for you center bolt wire looms. The set up couldn't look any better but it seems like the car is not going into closed loop like it's supposed to be. The car also has a gutted cat, 2.5" cat back with dual 2.5" tail pipes. Do i nead a heated O2 sensor or what?


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1989 Iroc-Z TPI 350 auto 4-spd Removed MAF screens K & N filters, stock other than that.

 

If you messed with the O2 during the swap it could have been damaged.
If you think the O2 is not heating up enough you could try wrapping thermotech around a couple of primaries and the collector.

good luck
ODB

 

How easy is it to damage an O2 sensor? It is almost brand new (about a month). Could i have screwed up with the plug wires? It runs smooth above idle but seams to be running in closed loop. It also backfires when you rev it and let off I'm assuming that's because it's running rich in closed loop with a gutted cat.

 

You're probably going to need a heated O2 sensor. Unless you dropped it or banged it around I'd say it's not damaged. I have heard of several people having to do this after going to headers. Did you jump the A and B terminals with the engine running (do NOT start it like this) and see if it is going into closed loop by watching the SES light? That's what I would do first, and then proceed with troubleshooting.

 

yeah i did the jumper a and b thing and it shows that it's running in open loop. When i hold the revs up for a few minutes it will blink like closed loop but when i let off after like 15 seconds it will go back to the quick blinking.

 

More exhaust flow = more heat = enough for closed loop. I'd say you need a heated EGO. Or you could try ODB's suggestion first and see if that helps because that might be enough to solve your problem. Anyone with a second opinion?

 

Wrapping the headers is no good for me, it'll void the waranty. Plus doing that is trapping more heat in which would also be fixed with a heated O2 sensor.

 

if the o2 sensor bung is in the incorrect place then it'll never operate properly! dont know how to tell if its placement is off without actally seeing it. oh yeah i had a set of accel 6mm plug wires and they were not a very quality product they seemed to glow in the dark when the engine was running in the dark spark scatter and lots of it! try going back to your p;d wires and see if it gets any better? if not we'll go to the next thing!

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1989 firebird formula

Mods: converted from T.B.I. to a carburator 305 to a 350. Flowmater exhaust,hedman shortie hedders,202 160 (882) heads,.447/.447 lift 222@.050 duration speed pro 327/350hp cam 350 .40 over (356) Edlebrock torker2 and a 600 edlebrock manual choke (1405)

Future mods performer rpm air gap intake (polished) comp roller cam, and way better headsa 400 defintely in the works!

[This message has been edited by burnoutrpm (edited February 12, 2001).]

 

The O2 sensor is in the collector which sits at the same level as the oil filter. The car runs smooth at 1500 and above so would that rule out spark problems? Thanks for all the help, keep it coming

 

New info,

you say that it backfires.
If it backfires under load (while acellerating) then check your wires for crossfire.

If it backfires when you let off the gas, then you just have exhaust leaks. Exhaust leaks at the header flange will cause popping in the exhaust, kill power, and likely be affecting your O2 readings.

good luck
ODB

 

Cool I was thinking that my self. It doesn't backfire under load only when you rev it in nuetral and let off. Would exhaust leaks keep the sensor from hot enough to start reading? Thanks alot.

By the way i checked on the 93 vette heated sensor and it's over 100 bucks through chevrolet.

 

I found the exhaust leaks, both collector gaskets were burnt out already. I bought a set of mr gasket ultra seals and an installing them in a little while. i also found a heated 02 sensor and am installing it this weekend. Should this fix my problems?

 

I bet my money on your plug wires being out of order. Especially if it backfiring. I had the same problem after installing my headers, took me two days to wire it up right. Check to see if any tubes are cool after the engine runs a couple minutes.

 

I had to use solid metal donut gaskets on my shorties. Any other gasket would blow out in less than a day.

 

Another update. I got all the leaks fixed, and put in the heated o2. The car runs in closed loop now like it's supposed to. BUT it now backfires under load. I checked the plug wires at night and don't see any arcing. Did i screw up when i crimped the ends of the wires. I checked the resistance of all the wires and all seemed to be close to the same. Somthing like 9-10 kohms? Is that acceptable or did i jack up somewhere? The only other thing i saw was on the rotor. Is the metal tab supposed to be up a little or is it suposed to lay flat? Thanks for all the help.

 

Bend it up a little, if it's flat you won't get a good contact to the coil. That could be your problem if it's flat.

 

Cool, maybe that's all it is. If that's not it i'm gonna yank those plug wires and say **** on acell for life. lol. Thanks again

 

I wouldn't run plug wires with any more than 600 ohms. I'm not sure what your wire is supposed to measure per foot, but you may have messed up the ends. If you run resistor type plugs and they measure over 6000 ohms that may contribute to the problem.

So now you are backfiring while accelerating? not when you let of the gas?

 

Yeah i'm backfiring under load and not when i let off. It was backfiring when i let off cause i had already burnt up both of the paper collector gaskets that came with the headers.

 

Well i bought a new cap and rotor and when i put it in i decided i would just disconnect all the wires and hook them up again to make sure i had the order right. Turns out i had two wires switched, damn i feal dumb. Thanks for all the help. It runs perfect now amd sounds good too.

 

We have a winner!
somebody pay up.

say this over and over to yourself
18436572
18436572
18436572

 

Posted by ODB:
Really?!?! I must be losing about a 100 horses, cuz my $hit's leaking bad at the collector.
sup ODB?

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'88 GTA 350
Headers, catback, free mods, Xtreme energy cam, intake pieces and 2100 RPM TQ

13.39@102.50 MPH
1.90 Sec ------- Best 60FT
104.23 MPH -- Best Trap Speed
AIM HIGH!

 

I figured i'd start simple so i went to auto zone and bought some mr. gasket ultra seals. They have a metal layer in them and seam to be sealing really good so far. It's amazing how much power you have when your actually using all 8 cylinders. lol.