Okay this is becoming frustrating. I have a problem with the engine not running properly. Upon starting, it sputters like its going dead, then immediately jumps up to about 1k rpm where it should be. It acts like it might idle fine but it misses a little bit for about 20 seconds then falls to 600 rpm and just chugs between 600 and 500, engine shaking and all. When accelerating, it misses a lot, and in no particular pattern, up until higher rpm where it runs fairly smooth. It feels weak on power, too.

What I have figured out so far: Engine spits out an 11 on the CEL when running diagnostics. That would be for cam sensor/crank sensor/timing belt skipped 1 tooth or more.

TPS is fine. Idle Air Control motor is fine. EGR valve and solenoid are fine. Ignition coil, plugs and wires are all fine. 02 sensors fine. Vacuum seems to be good everywhere (unless I just haven't found a leak somewhere).

Upon testing the cam sensor I discovered that the PCM was only sending 8.8 volts to the cam and crank sensor. Nonetheless, supplying the sensors with a healthy 12.5 volts didn't help the problem. The cam sensor was fluctuating between .04 and 5 volts output on the signal wire during turnover. I haven't tested the crank for signal output due to lack of helping hands and space under the car.

Now I seem to have hit something of a dead end. Is the low voltage coming from the PCM something to look deeper into? Could it be a symptom of more extensive PCM problems?

Also, can the engine exhibit the symptoms I gave you if the timing is off just a little? It wasn't off by much but when I changed the timing belt a week ago, the timing mark on the crank may have been off by a tiny bit.

And lastly, how worrysome is a messed up balancer pulley? We broke a small peanut sized chunk out of mine right near the inside lip using a puller. We welded it back in and smoothed it out as best we could, but I don't know if that could have any effect on these types of things at all. Just throwing that out there for good measure.

Anything I missed? ALL suggestions are welcome. I am in a huge bind with this one. Thanks a lot folks!

was it doing this before you changed your timeing belt?

Yeah. I kind of ignored it because apparently the check engine light bulb was not working so I just wrote it off in my mind. I don't think it was as bad before though. It is idling REALLY rough. It sat for a while while we were trying to get that stupid crank pulley off so I am having a hard time remembering exactly what it did before since I wasn't paying it much attention at the time.

Check your timing, and also check for a faulty MAP sensor.

Did you make sure your dowell pincs were okay on the cams?

I'm going to go over the timing today and make sure it is perfect. As far as the MAP sensor goes, I haven't tested it because the repair manual doesn't tell me how (or I cant find it anyway). Know where I can find some info on how to do that?

I really like your eclipse BTW. How bout some more pictures?

Oh... dowell pins? Not quite sure what those are. I will look them up but the answer is No. I havent checked them.

check the engine coolant temp sensor. i had similar symptoms and thought it was timing... check it to see if its unplugged. are you throwing a code?
>

98 eclipse RS

stage 2 cams + basic bolt ons = still slow as shit

DSM- Developing Smarter Mechanics since 1990

Its giving me a CEL code 11. That is for cam sensor/crank sensor/timing off 1 tooth or more. I'm not sure I trust the PCM at this point, though I have nothing else to really go on. I haven't checked the temp gauge because it seemed unrelated so I will do that.

Originally posted by Fooldog01
Its giving me a CEL code 11. That is for cam sensor/crank sensor/timing off 1 tooth or more. I'm not sure I trust the PCM at this point, though I have nothing else to really go on. I haven't checked the temp gauge because it seemed unrelated so I will do that.

i thought the same... turns out, that lil sensor not plugged in can mess with you ecu and throw off your fuel maps and ignition timing. do you have an upgraded valvetrain?



>98 eclipse RS

stage 2 cams + basic bolt ons = still slow as shit

DSM- Developing Smarter Mechanics since 1990

Originally posted by rs_sleeper98

Originally posted by Fooldog01 Its giving me a CEL code 11. That is for cam sensor/crank sensor/timing off 1 tooth or more. I'm not sure I trust the PCM at this point, though I have nothing else to really go on. I haven't checked the temp gauge because it seemed unrelated so I will do that.

i thought the same... turns out, that lil sensor not plugged in can mess with you ecu and throw off your fuel maps and ignition timing. do you have an upgraded valvetrain? >98 eclipse RS stage 2 cams + basic bolt ons = still slow as shit DSM- Developing Smarter Mechanics since 1990

Correct because it will usually tell the PCM that the engine is cold, and then the MAP will add more fuel and cause it to run shitty and rich. Most times though, it will not set a code for the Coolant Temp sensor because even if it is reading wrong, the PCM is correcting it by adding/taking away fuel, if you know what I mean.

My mods are all bolt on. The temp sender is plugged in but I am going to pull it for testing. Right now I am in the process of doing some more testing on the IAC motor to be sure it is working exactly right.

Originally posted by Fooldog01
My mods are all bolt on. The temp sender is plugged in but I am going to pull it for testing. Right now I am in the process of doing some more testing on the IAC motor to be sure it is working exactly right.

Problem is that you cannot really test the CTS (coolant temp sensor). Reason being is, it still sends a reading to the ECU, rather it being right or wrong. The only reasonable way to test it is to look at it with a Scanner to see what it is sending to the ECU.

lemme know what happens and good luck :)
>98 eclipse RS

stage 2 cams + basic bolt ons = still slow as shit

DSM- Developing Smarter Mechanics since 1990

Any ideas on testing the iac motor? Its got 4 prongs and 2 are 12 volt. I cant figure out how to make it extend.

the best way to test it is basicly to just unplug it. if there is a drastic change in the way the car runs/idles when you unplug it it should still be good. if there is no change at all then its bad. that is the easy non techincal version to check it. im sure there is a better way but that should give u a ballpark of if its good or bad.

In that case, the IAC seems to be fine. I need to determine how to test the MAP sensor I guess. Once again, the crappy Chilton manual sucks and doesnt tell me how to do it.

Originally posted by Fooldog01
In that case, the IAC seems to be fine. I need to determine how to test the MAP sensor I guess. Once again, the crappy Chilton manual sucks and doesnt tell me how to do it.

Have you checked your timing yet? Check that first!

the MAP sensor i cant really help you with. first off i would check the timeing first and if its right on i have a cuple spare IM i can sell you a MAP sensor pritty cheep to determin if that might be the case.

Timing... right. I just figure while it was operating I would check some of this other stuff. But I have another problem. I was following the direction from somewhere on here I think, and I was cleaning the MAP sensor and I think it is shot now. Im throwing a CEL code 14 which is for MAP and the car won't run, so yeah, I will need to buy a MAP from you, Heh heh. Alright. I will go get right on the timing. I guess I won't be able to confirm anything until the MAP sensor gets here though cause the car wont run.

ill sell u a map sensor for $10 shipped do you have paypal?

If there's no vacuum leak and timing is correct, I'll also lean towards the water temp sensor and/or connector.

The stupid timing belt is so hard to get to, I got down to the crank pulley last night and went to bed. I'm hoping to make a determination on the timing today, but I have to get that stupid leaky head gasket fixed so it will be next week before I can get the SOB back together. Thanks for all the help so far though.

Alright well I have good news(I think). The timing belt had skipped and at TDC the cam sprockets were off 1 tooth. I suppose this was my problem. Now I am wondering how to make sure this doesn't happen again. What procedure do you follow when installing the belt? Do you push the tensioner up as far as you can before you bolt it in and pull the pin out of it?

Ahh I knew it was your damn timing!

Get a new tensioner, a hydraulic one like the OEM style and just follow the steps in your Haynne's or Chilton's manual.

The hydarulic tensioner seems to be fine. There is some area to play with it's position I am sure you know, with the bolt holes. Would it be fine to push it up as far as it will go and bolt it down and then pull the pin on the plunger?

Originally posted by Fooldog01
The hydarulic tensioner seems to be fine. There is some area to play with it's position I am sure you know, with the bolt holes. Would it be fine to push it up as far as it will go and bolt it down and then pull the pin on the plunger?

Thats what I do.

well im glad you found out what it was now this damn tread was starting to get long! now you know what to do next time something like this happens...