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View Full Version : HELP: 16 V missing at high RPM!!


epike7915
09-06-2006, 08:08 PM
my post on zuwharrie and update post---HELP!!
http://bbs.zuwharrie.com/content/topic,44109.0.html

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UPDATE: Still PISSING ME OFF!

-Tightened & added grounds from dist to block, block to battery, battery to firewall and grounds by ecm to firewall.
-Adjusted valves all pretty good one #4 exhaust valve was tight so we fixed that
-Checked compression, all with in specs 1-3 155psi #4 135 psi
-Checked timing was good at 8* degrees per Haynes manual. Total advance at 3500 rpm ~33* degrees total

The miss/backfire is coming on at just above 5500 rpm at a free rev or under load at same or close rpm. It sure sounds like it is popping bad out of exhaust/tailpipe.

We did notice when check total advance just as the motor would start to backfire it would show a drop in timing somewhere from 5-10* degrees, as if something was pulling timing out of it or above that 5500 rpm threshold... The only code it is pulling is p0135 which in our book shows #1 o2 sensor HEATER CIRCUIT MALFUNCTION. So I bought a new $100 front O2 and reset computer and same problem and the code came back on.

As an "old school thought/test" per my old man , we even tried unhooking the front (#1) O2 to see if anything changed as far as running or idling or timing and none of these changed. It ran Exactly the same. In my dad's "old school" thinking it he points out that either that o2 or that o2 circuit is messed up (BACK TO THE p0135 code?) Anyone know EXACTLY what this code is saying and what controls/sends this code, some sensor, wiring or ECM???

I need to mention that this was not a "Trail Tough" harness it was done by a mechanic friend that has done 3 or more of these without this particular problem. He did note to me that this ECM was different then any he has done by it having 3 plugs at the ECM, (again it was out of a 96 tracker with automatic). Also, there is no VSS hooked up to speedo and the 2nd (rear 02) is not hooked up (but I don't believe either of these would cause this)

Any input thoughts are DEEPLY appreciated! I am going to a pretty big pig roast/ 4 wheeling party this weekend where there will be alot of HEEPS and I can't have this poop popping and backfiring everytime I need to kick it in the [censored] thru deep mud or high/loose hill climb that I can't crawl. (CRAWLING IS NOT AN ISSUE!)


Eric

Itsmejoe231
09-06-2006, 08:13 PM
Are you sure it is not the rev limiter coming into play early?

epike7915
09-06-2006, 08:24 PM
It is funny that you say that, that is the first thing I thought was happening! How do you find out/fix?!

Eric

Itsmejoe231
09-06-2006, 08:43 PM
That question is beyond me. I am sure someone can/will chime in and let us know.

I dont know what drives the rev limiter. I dont know if it takes power from the distributer when it kicks in or what.

epike7915
09-06-2006, 11:45 PM
yeah, anybody??:eating:

Joe Edge
09-07-2006, 09:01 AM
my 16 valve was put in before i bought it.mine is out of a 97 tracker, i think it was and auto cause when i pulled the codes off my ecm they said shit about the trans but mine doesn't skip. i didn't read your entire thing but my 98 s10 one day made a huge backfire then shit out and everytime i tried to start it would crank, crank then backfire. it was my rotor and cap, you probly replaced those but if not try it.

epike7915
09-07-2006, 09:49 AM
my 16 valve was put in before i bought it.mine is out of a 97 tracker, i think it was and auto cause when i pulled the codes off my ecm they said shit about the trans but mine doesn't skip. i didn't read your entire thing but my 98 s10 one day made a huge backfire then shit out and everytime i tried to start it would crank, crank then backfire. it was my rotor and cap, you probly replaced those but if not try it.

No, Joe, mine runs good till 5-5500 rpm, crawling is fine, it pops under load as well as when free revving it. Cap, rotor, plugs and wires are BRAND new.

Eric

DesertZuki
09-07-2006, 08:55 PM
The miss/backfire is coming on at just above 5500 rpmI was told rev'ing a 16v above this RPM is taking a chance at having a rod come through the block. I've rev'd mine up to 6k, but only because I wasn't paying attention. Mine feels like the power band drops off after 5500.

It sure sounds like it is popping bad out of exhaust/tailpipe.It sounds like you've already figured this out, but backfire out of the tail pipe = retarded.

It ran Exactly the same. In my dad's "old school" thinking it he points out that either that o2 or that o2 circuit is messed up (BACK TO THE p0135 code?I'm by no means a genius when it comes to this stuff, but I don't understand what an O2 sensor would do with retarding the timing that much. And I don't know what the code means.

it was done by a mechanic friend that has done 3 or more of these without this particular problem. He did note to me that this ECM was different then any he has done by it having 3 plugs at the ECM, (again it was out of a 96 tracker with automatic)My harness put together by someone who used to install stereos. I have three plugs in my ECU. I also have the 16v from a '96 Sidekick, 2WD Auto. I'm not running the auto in the Sammy.

there is no VSS hooked up to speedo and the 2nd (rear 02) is not hooked upDitto here. And I don't have this problem.

Any input thoughts are DEEPLY appreciated Sounds to me like whatever is supposed to advance the timing is failing and it's not giving you a trouble code. I'm ashamed to say I don't know that much about it and I have your same engine.

Did the motor always do this or did something change and then the problem started?

Is the fuel system functioning properly? Would a lack of fuel under the high demand of the high RPMs cause missing and make the computer try to compensate by retarding the motor? (Just guessing here)

I'll continue to think about this. It sounds like we're running the same set-up, so if you have a question I might be able to help with, ask.

epike7915
09-07-2006, 09:16 PM
[QUOTE=DesertZuki]I was told rev'ing a 16v above this RPM is taking a chance at having a rod come through the block. I've rev'd mine up to 6k, but only because I wasn't paying attention. Mine feels like the power band drops off after 5500.[QUOTE=DesertZuki]

Sorry, but I know this is false for SURE. A buddy of mine has a 16V in his and factory rev-limiter in his hits at 7200 rpm. The 16v may drop off in power before there but they do make power up there. (Just not mine right now) As far as if it had this problem before the swap, I don't know. I didn't rev it that high when it was in the tracker. In normal trail driving/crawling like I said you will never notice it. You only notice it when you have a high loose hill climbs ( like big hills in the dunes/sand at the badlands or in DEEP mud like back in Orange at the Badlands when you have to get in it to get "unstuck".) Or if you free rev it above 5000 rpm....:confused: