Adam, please, trust me.

Closed loop is using the o2 sensor for trimming, (idle, low-medium load)

Open loop is not using the o2 sensor, just using the map (High-WOT load)

This is why denis' turbobox works so well, it just pushes the car into open loop whenever we want so the ECU wont fight back, because it isnt paying attention to the O2 sensor



from the wikipedia page HERE

look at automotive applications

 

*lol* So the CEL turned off on its own yesterday when I drove the car around the block, but the other symptons still remain:

- Power when its cold, but when it warms up, no power at all
- Idle dropped when stopped and almost stalled a couple of times
- Engine still sounds like its working extra hard when I punch it, with no exhaust tone out of the muffler


I'm sure it'll turn back on sometime or another when I drive it again.... mad.gif

 

since I'm sure you double checked the maf then I'm going to have to go with 02 sensor. but I don't think it would cause all of that. no o2s at all would just cause super rich conditions. you could unplug it and see if that helps.

could be fuel pump as well. or vacuum leak around the fpr... only one cel? whats the number?

 

So ok...got the car back this morning, and they did all kinds of tests on it.

- Fuel pressure is perfect (not running lean or rich)
- Spark is perfect
- No vacuum leaks anywhere
- MAF is fine

The only thing they saw was low compression when they did a compression test, which means bad rings. They took out the O2 sensor, checked it (no buildup on it), checked the voltage on it...everything was fine. They cleared the CEL, and it didnt turn on. I drove it around for a bit, and all the same symptons were still there, except no CEL obviously. So, if all these issues are because of bad rings and low compression....how hard is it to replace them? I know it involves to basically rip apart the engine and all that. But is this something that can be fixed in a day by someone who knows how to do it (I would have to find someone local that knows how). Also, are there aftermarket rings available or would I be better off just getting OEM ones? What about getting some kind of additive to dump in that restores compression and stuff? I have always used Synthetic oil, and will continue to use it.

Any other ideas or suggestions? Thanks everyone....

 

Did they give you the numbers back from the results of the test, or did they just say, "your compression is low" ?

 

technically, you could do it in a day. the actual replacement of the rings is not hard. Just pull the pistons out, deglaze the bore, pop new rings into the grooves, and compress before inserting into the block. It is EVERTHING you have to do to get to the point. Remove the engine (you could do it with the engine in, but who would want to?) pull the head and oilpan. then you need to undo the rods from the crank, pull the pistons, replace the rings, insert back into block, put in new lower end bearings, and then button everything back up.

What you need to do now is a LEAK DOWN TEST. you need to figure out why you have low compression. A leak down test just forces compressed air into the cylinder while at top dead centre. With both valves closed, you remove the oil cap, radiator cap, and open the thottle butterfly and then listen. Air coming out of the oilcap is probably bad rings (could be a bad headgasket too). Out of the intake or exhaust, bent or burned valves, out of the radiator, blown headgasket.

Once you have a better idea of WHY your car has "low compression" you can figure out how to fix it.

It just seems odd that it ran great BEFORE you had the exhaust work done and shitty afterwards. perhaps you should unhook the exhaust manifold from the rest of the system and take the car for a SHORT drive (bring ear plugs, or your ears will bleed from the noise) and see if it runs right again

Another thought that occured to me from my days with cars that have actual distributers.. how is your timing?

If your timing is too far retarded (coming after top dead centre, you will loose power higher up in the RPM band, have super lousy miliage, and generally the car will run like crap.

besides being off at the crank sensor, check the Throttle Position Sensor AND the knock sensor. Both of those affect the timing of your engine. This can give you the "Wide open throttle sound" without any power to back it up if the timing is being pulled way back by either of these sensors. Considering how crappy the TPS is on the tib, I would start with that one first.

 

Thanks Mad. I think Im just gonna follow the advice of what was said in another thread by someone else, with similiar issues.

I found a new 2.0 engine with VERY low miles and its pretty inexpensive, and I have a shop I trust that will drop the new engine in for only a couple hundred dollars. It'll take them less then a day to do it. So I'm just gonna go that route. I have a 2k1, and its got some pretty high miles. So this will probably just be the best thing for me to do, than to get a rebuild kit. The current engine, I'll just trash instead of trying to build it up. The only engine mods I have is an AEM CAI, Header, 2.5" piping, Onpol Special bored BBTB and IM (those of that were around when FxTreme was up will remember Onpol), 1.8 cam, and stage 2 clutch. I was running a 55 shot of nitrous not long ago, and that could of possibly what killed my rings, but I hardly doubt it. Im running colder plugs and better wires, as well as a high flow fuel pump. So I dont see how that could of killed the compression. But you never know. Weirder things do happen. *lol*

Anyway, I'm sure once I get a new low mileage engine in the car, it will be like brand new and all will be well. I'm waiting for the NGM SC to hit, as is alot of people, so once thats out in the market...I'll start making plans for it.

I just wish I knew more about engines. *lol* Ask me anything about paint, body, and suspension...and I can answer. But ask me anything about engines and tranny's and I'm clueless. *haha*

Thanks again for the help....

smile.gif

 

You're going to just take someone's word for it, and go through all the work of an engine swap, before even seeing the actual results of the test?