Engine Rebuild not running well

[Andrew7DG]

Ok so my car is a 1993 Mitsubishi Eclipse GS Non Turbo

A while ago the pistons hit the valves due to the timing belt snapped. I took the engine completely apart and then I put a head from a turbo on it to replace the one with bad valves. So I managed to get everything put back together and started it up. It is running really rough though. It revs to the higher RPM but not very well and does not idle. It has some backfire issues but I played with the timing and that goes away i think. I thought it was the timing for a while but after playing around with the settings it did not help. I think it could be the timing belt itself however i am pretty sure I got all the markings lined up. Can anyone think of stuff I should look for before tearing apart the engine again to look at the timing belt. Loose plugs I should check for? Anything?


Thanks!

 

[grnchevyz]

I'd perform a compression test to see what's happening. Let us know what you find and we can take it from there.

 

[Andrew7DG]

Ok just bought myself a compression testor and did the test the results are 165-160-150-170 so they are all close of each other i believe. I do think they are a little low from where they should be but this shouldn't cause the rough idle or no idle.

Also I wanted to make sure the timing belt was infact put on right and I put the engine at top dead center and looked at the gears and they all line up correctly so I do believe that everything is good there.

So now I am going to search for new ideas on what is wrong. The gas has been sitting in there since march so a can of sea foam is going to get added to the tank, A new set of spark plugs are going to be put in as well

Anyone with new ideas???

 

[Andrew7DG]

Ok

I hooked up my Palm DataLogger to the car just to see if anything can be helped. So What I found was that the COOL reading (which must means the coolent) was -75 degrees. Looked at the sensor itself and the wiring was cut. This is the sensor pn the side of the engine by the cooling cap

So my question is, is this sensor causing the problems.WTF I didn't think it would cause this much problems but maybe it does. I am going to replace it. Could this be the problem or doesn't this sensor play a big part in the computers math?

 

[TurkF26]

With a bad/broken/wire cut coolant temp sensor, your car will do some really weird things. The car is not designed to run well until it reaches a nominal operating temperature. If the ECU thinks that the coolant is at -75 degrees, it is going to do whatever it can to raise that temperature which means a car that does not run to well. I would definetly fix the wire going to the sensor and it should take care of all your problems.

Im not too familiar with what a N/T 4G63 compression is suppost to be but 150 i think is a little low??? When you say you had the motor redone, did you do anything with the bottom end or just replace the head?? Was there any significant marks/chips/etc... on any of the pistons from when the valves hit them?? Did you use a stock headgasket/MLS???

 

[grnchevyz]

Turk, his car is a GSX not a N/T so the compression seems to be good. The 150 is low but not bad.

and yes if the ECT sensor is malfunctioning it will create all sorts of funky fun little things with your engine. Fix that wire as soon as you can. It should resolve most if not all the issues. That's hoping no more damage was done while the engine was trying to compensate for a -75 degrees collant temp

Cheers!

 

[TurkF26]

grnchevyz, did you not read his original post??? He said he has a 1993 GS Non turbo and put a turbo head on it. Most likely he has 2 1g's, a N/T and a GSX. I know that the compression on the 4G63T is fine to have around 150-155 but i dont know what is considered good and what the service limit is on the N/T 4G63.

 

[grnchevyz]

My bad.....but the compression although within specs, seems very low.

Optimal is around 192 and service limit it 145 on a N/T Engine

 

[TurkF26]

its cool man...

ya i would just replace the temp sensor and see where that leads him. If it still runs like crap, then he may have some ring/piston damage. I would really like to know when he replaced the head, did he inspect the pistons at all for damage and what kind of headgasket was used.

 

[Andrew7DG]

YAY! PEOPLE RESPONDED!!

Ok to start off, I do have two eclipses. They are both fun to drive.

To tell you what I did to the car,

Took the engine out completely with transmission

Took the engine apart till it was a short block.

The pistons have a little nick in them but that was all. It is just the area that came into contact with the valves. I have pictures if you are interested but like I said just a little nick. Someone told me that they were fine. However I have been warned that I should replace the rod bearing. So what I did without taking the piston out of the engine I turned the engine over to the bottom end and just replaced those. The old ones were fine I believe but my dad wanted me to replace them anyway

I reasembled the engine

I replaced the head completely with one from a turbo. I heard that they are basicly the same engine and that it should work. All that is different is one cam

I did use a mitsubishi head gasket right from the dealership so I believe I am ok there

When we did the pressure test the car was pretty cold and in the book it says to do an accurate compression test you need to have the car warmed up. However since the car doesn't run well I didn't want to risk it.

I haven't yet replace the sensor but that is the only thing that I can think of to do next.

What bugs me is that the car sounds like it is running lean

I will post a video soon and see what people say

 

[Andrew7DG]

here is the video


Just to let you know it doesn't idle well at all before 1500 rpm

Plus this is what we thought the timing belt wasn't lined up correctly but we checked the cams with the bottom end and they all line up. Crank is at top dead center and lines meet up with eachother on the cams

 

[TurkF26]

Did you have the head deck/hot tanked/ inspected by a machine shop before you put it on or did you just throw it into the block along with the headgasket?? There are differences between the turbo/non turbo blocks. The most significant is there are no oil squirters on the N/T blocks along with other things too.

I would replace that sensor/fix it and let us know how your car runs after that.

 

[Andrew7DG]

Ok replaced sensor and still not working.

I was at a rally race and talked to a person there and they said you may have to flip the cam sensor 180 degrees and I did. I believed that helped in the higher RPM however when it goes back to idle it still dies.

Another Idea that I had was that it may be the timing belt tensioner is bad and gets the timing belt loose. Does anyone know the symptom if that happens?

I really don't know what to do at this point. I checked to see if there are any vaccume leaks and there isn't.

I didn't get it hot tanked or inspected. I trust the person that I bought it from. So it isn't like it came from a junkyard or anything like that. I just put it on. The compression numbers are fair so I think that wouldn't be causing the bad idle.

I don't think I need the oil squirters on the N/T block. I am just using the head off of a turbo block and just plugging the oil lines.

 

[Andrew7DG]

Ok we just took it for a test drive for the heak of it. It will drive under its own power pretty well above 2000 RPM below that it starts to hesitate like it would at idle. So it has power! but still doesn't run right

So again I am wondering if it is the timing belt tensioner?

 

[92DSMErdrick]

check timing marks, my old N/T when i did the timing belt it was off by one tooth and it sometimes died at idle but drived fine once you had ## foot on the gas. Double check it to make sure all timing marks line up

 

[1stGenRocks]

clean the tb and isc. you probably should check/adjust the base timing and set the idle speed also

 

[Talonman92]

The same thing happend to my '92 N\T talon. We did a re-ring job and just cleaned the pistons up as best we could. They had some marks from where the valves hit them but nothing huge. The car has been running fine ever since with almost 6k miles on the rebuild and it burns no oil and still runs like new.

As for why the car is stumbleing... This might be a long shot but here it goes... (skip to the end if you don't wanna hear the story)

My mom's oldsmobile acheiva (worst car design evar) blew a head gasket and was basically running on 3 cylinders by the time my brother and I got to it. We replaced the head gasket and had the head milled. Once we got it all back together we fired it up and it ran like complete shit. We were stumped for about 2 weeks. We were just about to chalk it up to the acheiva being a POS to begin with when my brother was messin around with the coil packs. He swapped some other ones we had in the garage in and fired it up. Low and behold the achieva ran like a champ.

So my suggestion to you would be to check the coil pack!!