Engine misses going up hill

[kmacht]

Ok. I have been searching around for the past few days and can't find a thread with a similar problem. I have a 94 1g 1.8 NT completely stock eclipse. The car has been running perfectly up until two weeks ago. Mostly when going up a hill at around half throttle the engine misses. It doesn't do it all the time and seems random when it does happen. It has done it a few times on a flat stretch of road as well but most of the time it is when going up a long stretch of hill. I am usually in 4th or 5th gear when it happens. The car accelerates fine from a stop and doesn't appear to be loosing any power all the way to redline. The best way I describe it is it feels like there is an air bubble working its way through the fuel line. The car hesitates for a second and then resumes driving normally. Somtimes it just happens once and sometimes multiple times in a row. It happens so fast it doesn't even really register on the tach. You can feel the hesitation and hear it through the exhaust. I have pulled the plugs and they all look good with no fouling. The car has newer cap, rotor, wires, and plugs about 10,000 miles ago. I tried pulling the maf sensor and the car wouldn't run without it so I'm thinking that it is working fine. I'm at a bit of a loss here. Any ideas where to start? ECU? Fuel pump? Fuel Filter? Some other sensor?

Keith

 

[dsmreck]

More info is needed for help.... The problem is if it is random it can be very hard to diagnose...at or mt

 

[pauleyman]

Done a tune up lately?

 

[Mischif]

One possibility could be a bad tps or loose connection for it. Happened to me before. One of my tps wires was barely connected whick caused an almost consistent miss about 75% of the time under acceleration. Took me forever to figure it out since my tps looked fine when logging it. Could also be a bad injector.

 

[kmacht]

Still struggling with the problem. I have changed spark plugs, wires, rotor, and cap with no change. I pulled the connector from the TPS sensor and had no change other than the check engine light coming on. I checked compression on all four cylinders and they were all right around 125. The only ignition piece I haven't replaced is the coil (its on order). I checked the spark with a spark tester (the type you can adjust outward until it starts missing spark). The tester was good right up until you went just past the 30kv marking. Not sure where to go from here. Any suggestions?

Keith

 

[mitsubishimanic]

i would say fuel system check the fuel filter first, sounds like its plugging up. when was the last time it was replaced? if it you have never repelaced do it its like 20 bucks.

 

[kmacht]

Forgot to add fuel filter to the list of things done to the car. That was the first thing I replaced with no affect. I would like to check fuel pressure while driving but the 1.8 engine doesn't have a test port anywhere in the system to hook the gage to.

Keith

 

[pauleyman]

Checked ignition timing? 125 is also pretty low for any NT. Was the car warm at the time? It should be.

 

[Mischif]

Did you have the throttle plate wide open when you performed the compression test? If you did the test correctly and 125 is what you got, then that could very well be the problem. According to this site your below the service limit. How to do a Compression Test. Have your verified that all your timing marks for the timing belt line up?

 

[kmacht]

The compression test was cold so that is why I'm not too concerned with the low numbers. I was just trying to get a feel for how each cylinder was to one another. I was hoping that one would be significantly lower than the rest giving me a direction to look in. I haven't checked timing but don't see why it would be off. The distributed hasn't been moved or adjusted since leaving the factory. This is a problem that just popped up one day after driving perfectly for the past year. I didn't change adjust or modify anything before it started happening. Is there a FAQ or thread on how to check timing on a 1.8 nt? I don't think it's the problem but I'm willing to give it a shot

Keith

 

[Mischif]

Even for a cold engine those are really really low numbers.

There is a vfaq that covers timing on the 2.0, which is almost identical for the 1.8 minus a cam gear. Basically remove your water pump and crank pulley. Remove upper and lower timing covers. Turn the crank clockwise until the timing mark on the balance shaft gear lines up with the small triangle on the front case( the mark is around the 10-11 oclock postion). When that is lined up the cam gears timing mark is supposed to line up with the mark on the rear cam gear cover. If it doesn't line up turn the crank a full rotation and line it up with its mark again. If the cam gear still doesn't line up with its mark then your mechanical timing is off.

 

[DSM1G90]

There's an easier trick to see if mechanical timing is off: Just take the upper cover off, start the motor, clip on the timing lights' connector to No. 1 plug, point it to the mark on the back cam plate and see where the dot on the cam sprocket comes into play. Dot should be almost two teeth to the left of the mark on the back plate to be close to 5* BTDC....with the ECU terminal clipped to chassis ground with a jumper wire.

I'd call it base timing is off. Base timing is the same as with the 4G63: 5* BTDC with the ECU terminal clipped with a jumper wire to chassis ground.

My little 1.8 automatic was acting somewhat the same way on an uphill grade and knew right off that the dist wasn't where it should be.

Did the base check and got my power back and then some (TPS was a little off as well and did the readjustment to get that all back where it belongs) The dist had rotated enough to retard the spark and the ECU was fighting to get things close to where it was to be.

Another thing to think about esp when wires were changed out: you get two wires that fire next to each other, the earlier one will fire the next one by conduction alone .. this is what's called "crossfiring" and that can mess things up also - get those wires separated.

DSM


Waste spark system that the 4G63 uses is so much easier.