Odd no "takeoff power" issue.

[markjs]

My 1990 Mitsubishi Miarage, 3spd A/T, 140K Miles, recently developed a problem taking off from stopped and dealing with hills. I did my best forum search and came up with the possibility of the "MAF" sensor being at fault? I have not recieved a "check engine" light though.

Basically it takes off into traffic painfully slow at first, then has normal power after about 10MPH. Also, if I try to start up a steep hill I can floor the gas pedal, but can't get much faster than walking speed, (we are talking very severe hill). On hills taken at speed I am pretty sure there is some power loss but it's not nearly as bad of an issue. It is not at all a transmission slippage issue, it's just as if all the car can do is idle up the hill espite maximum pedal. Also my gas mileage is signifigantly less than when I got the car. I have only a NAPA auto parts locally, so nobody putting cars on diagnostics for free, but I do have a friend who has one of the units and I intend to have him run it tommorrow. Is there any other thing that could cause this?

[markjs]

Oh and to further complicate? It is the California model....

OK, well I think I have ruled out the MAF sensor. As I said I have never gotten a "check engine" until I disconnected it and tried to run it and that made no difference to my issue. I am not sure if I will get any trouble codes if there never was a check engine light, but I disconnected the battery so that it would clear the codes. Then when I drive it to my friend's he can get the truest reading.

I have further refined my understanding of the symptoms though. I went to a very steep hill (which is where I first noticed that this was a real problem), and I tried to go up it. For a LONG time I could not get up to 10MPH, but just as it got above 10MPH it started to gain power, and at 15 it could actually accelerate slowly up the hill, and the faster I got the more power I had, though I ran out of hill. It seems to me that the only real problem area is on takeoff. If I get a running start at a hill it doesn't seem to be an issue.

Any power loss at normal running conditions is largely theoretical. I think there may be a little power loss but it's not signifigant enough for me to be sure, since I haven't even owned the car a year, and if there is power loss at high speed it isn't a huge difference. I do know that it did not have this problem on steep hills when I got it, or if it did, it has gotten radically worse. I am REALLY DESPARATE here, I am poor, live in a VERY hilly state, and even though gas prices are way down this car should get better than it's current 20MPG. Any ideas will be greatly appreciated!

[shorod]

Does the engine seem to idle smoothly? When's the last time the car had a tune up (spark plugs, plug wires, distributor, coil, fuel filter, air filter)? Have you inspected the vacuum lines and intake air tubing for cracks, missing hoses, or collapsed hoses? If the car hasn't been wrecked in the front, there is probably a vacuum diagram under the hood which should show you which vacuum lines should be there.

-Rod

[markjs]

I changed plugs, wires, cap, rotor, fuel filter, and air filter yesterday. I have not performed a detailed check of the vacuum system, but there are no obvious flaws and it idles perfectly.

The timing belt was done recently as well....

I should have posted this already, but thanks for the heads up!

Through further searching of these forums I found someone saying a plugged cat can cause this?

[markjs]

I think it was the cat but I have not fully tested it yet. I need to go find that really steep hill soon. I will let you all know....

[markjs]

New catalytic converter (it was plugged up pretty good), makes NO DIFFERENCE!

I don't get it, I have replaced every component that wears out commonly, and no check engine light, but something is still wrong?!?

Was it Auto Zone that will let you get the codes checked for free? There isn't one here, but about an hour away I am pretty sure there is one and also a Shucks.....

I really need this fixed!!! It is drivable, so long as I never get stopped on a steep hill, just about a month or two I went up the hills from the waterfront to downtown Seattle to downtown and those are crazy steep, but it seemed to be OK, I mean it was pretty slow and gutless, but nothing like it is now.

[LeSabre97mint]

Mark

By chance did this problem start after the timing belt was changed?

Regards

Dan

[markjs]

Originally Posted by LeSabre97mint

Mark

By chance did this problem start after the timing belt was changed?

Regards

Dan

Yes it did, and I now know what it is, but it's pretty horrific. Since it is an automatic we could not get the bolt that holds all the pulleys and the crankshaft sprocket itself to the crankshaft to have sufficient torque to stay in. It is listed as 62 foot pounds, but there is no way to hold the engine still easily. We ended up having to repeatedly put that bolt back in. I actually lost the original on a highway and was forced to drive several miles at high speed with nothing but belt tension and the timing belt cover to hold things together. The last time we put the bolt in, we used two kinds of lock washers and Loctite, and braced the engine through the camshaft sprocket using the timing belt to get the torque.

The thing never came out again, but the damage had already been done. We thought somehow it had skipped a timing belt tooth (since it is a round tooth type). The terrible reality though is that the vibration had destroyed the inside of the crank sprocket and the end of the crankshaft. See the crankshaft end has two flat sides of different sizes to keep it only able to be on one way, but now the inside of the sprocket has small half moons and the crank has small hills on the sides. I will most likely be without a car for some time to come.


We may be able to replace the crank sprocket at great trouble and expense and it will most likely work ok but technically the crankshaft needs to be replaced (although the damage is minimal enough I don’t think I will have further trouble provided I can get the damn bolt to stay in this time).

Does anyone have any ideas about getting that thing to stay in this time? I mean I think we can get the needed torque, but now I am paranoid about the whole thing!

[markjs]

Oh I also have some small concern because the original bolt fell out on the highway and we were just using a replacement from the hardware shop, as the bolt is not a part one can order, it has to come from a junkyard, but it as a unique looking bolt. Still it is a standard size and thread. This thing can't be wrong this time or the crankshaft could end up damaged beyond hope.