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The display panel shows the "check engine" icon and says "ENG PWR REDUCED" or something similar to that. Code reader gives: P0223, P0122, P0123.

About a year ago we started having timing issues. We ended up opening the timing chain cover, realigning everything, replacing the tensioner and putting everything back together.

Now, the starter will crank the engine but nothing else appears to happen except for an occasional "hit". At least one of the spark plugs is firing. There is fuel pressure and the fuel pump starts up during ignition. The throttle valve moves a little bit while the starter is cranking. The voltages on the throttle position sensor with respect to ground appear okay. The purple wire (reference voltage I believe) vs. ground is +4.91V and with the car turned on before ignition the "sensor voltage" vs. ground is +4.46V which comes out to a difference of +0.45V (reference vs. the sensor). I'm not quite sure what all the other wires are supposed to be so I didn't test those yet.

All diodes were tested and all fuses were visually inspected. The voltage does change when the starter is cranking, especially if the gas pedal is pressed (if I remember correctly).

I've tried too many different things to list off here (mostly simple "fixes" from forums like this) but nothing seems to work. I am as certain as I can be that we got the timing chain aligned properly and it was running before this--just misfiring. The car has been sitting unused for about a year and there appears to be a lot of dry-rot on the corrugated wire covers along with a significant amount of dirt/debris inside the engine compartment.

Our next step is a find an ECM from a salvage yard to swap. Anyone have any ideas? I am willing to do whatever it takes. If you need any pictures, voltages or other info in order to help just let me know. Thanks in advance!

P.S. If anyone can point me in the direction of a repair manual or electrical schematics for this vehicle I would also really appreciate it.


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Location: Oregon
you need to stop and take a couple minutes to figure out what you are trying to repair. It would seem that you have more than just one problem. The three codes you have are all for the TAC (throttle actuator control - drive by wire) and those codes will cause the reduced power condition. you will need to look at the two tps reading. they should match. you should use a scanner or some tool that you can graph both sensors to see if you have any glitches or drop outs. there are two tps signals and two processors that compare each other. if they don't match you get codes. because they don't match the computer doesn't know which one to believe so it reduces the power so you don't have a runaway engine. (just in case. it's a safety feature)

the other problem is your no start problem. starting from when you said you were having timing issues: what were the timing issues? when you aligned everything did the engine run normally after that? Or has the engine never been run since then? Have you verified that you are getting spark to each cylinder? Fuel injector pulse to each cylinder? have you checked the compression for each cylinder? Is the fuel pressure between 50 - 60 psi?


   
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I asked the person that experienced the timing issue before. It started running a little rough. Wouldn't idle properly. Went and got an oil change and after that it wouldn't start and was throwing a timing code (don't know the exact code as he doesn't remember).

I've checked one of the spark plugs (it's good) though I suppose I could check the others. I don't know the exact fuel pressure though it's definitely enough to cause the fuel to shoot out at least 3-5 feet when the valve is depressed near the engine.

The engine hasn't run since changed the timing chain tensioner and realigned the chain itself. I don't have an oscilloscope or anything that I could use to graph signals or voltages in a time-dependent manner. However, it is no longer throwing the timing code that my coworker mentioned. Also, I don't know how to check cylinder pressure nor have I ever worked on a fuel injector, though I'm certain I could figure it out.

I guess the first thing I need to ask is: will the car still be able to start in most cases if the "computer" is detecting that there's something wrong with the TPS? If so, it's probably some other major issue within the engine itself, right? I mean, it does have about 220k miles on it.


   
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the engine should be able to start with APP of TPS codes but it will say reduced power.

cars are complicated. do you have a crank and cam signal? There are many things that you can't guess at. You have to know. And it may take some special tools or special skills to be able to figure these things out. Before the timing chain was set and the crank was timed to the camshaft. the camshaft was timed to the distributor and it was pretty easy to see if something was out of whack. But in modern cars you have timing chain that has a tensioner. if you set the cam timing without taking the tensioner into consideration you could set it to the wrong timing. but now the engine spark and fuel injection pulse need to see the signal from the crank sensor and the cam sensor. It not just mechanical anymore. Fuel pressure needs to be within spec. If you have 10 psi below minimum spec it may not start. you may not be able to sense the difference between 30 and 50 psi in the fuel rail.

it should be easy to check injector pulse with an incandescent test light while cranking the engine. Or to check to see if you have spark when the engine is cranking.


   
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Well, now that you put it that way, I bet you we messed up on the timing chain/tensioner somewhere. Doesn't seem like there's much else it could be unless there is something else that has gone wrong since the car's been sitting there for nearly a year. Oh how wonderful it will be to take that cover back off and work on the chain without lifting up the engine. Still doesn't explain the TPS issue though... How would ******* up the timing chain/tensioner/cam-crank-alignment do anything to the TPS? It's all very baffling. I'm really thinking about buying that ECM I found just to rule it out since it's so cheap...

Anyway, thanks for the advice!


   
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you may have more than one problem. the throttle problem is easy to check with a scanner. clear the codes and see if the app sensors match up. the no start problem, check your engine for spark, fuel pressure spec and fuel injector pulse.


   
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