huge power loss, misfires, and unsteady rpm's - Hyundai Performance Forums

sage020 · 01-29-2003, 10:19 PM

Recently my tach started bouncing all over when at idle and when driving. At first I thought it was just the tach but a few days later if I let the car idle the rpms would get as high as 1600 and as low as 350. It bounces a while and then the motor dies. Not only that, but the car lost probably 50% or more of its power. The car doesnt jerk so I dont think it's the spark plugs and I changed the cat converter tonight but it still does the same thing. Now Im thinking maybe its the fuel pump but any help or better ideas would be appreciated.

vipergts_3 · 01-29-2003, 10:43 PM

if it isnt your fuel pump it could be your spark plug wires . my ex had a similar prob with hers and it was just faulty spark plugs hope this helps

sage020 · 01-30-2003, 01:16 AM

Spark plug wires crossed my mind but I thought that the car would chug while driving at steady speeds, but the car still drives steady. Ill look into it a little more yet. Thanks for the help.

skierd · 01-30-2003, 02:01 AM

check your plugs and plug wires (should be changed every 30k miles), fuel filter (30k), air cleaner (every to every other oil change).

mattgolin · 02-03-2003, 06:07 PM

Have you tried simply resetting the computer?
My car had a bouncy tach for a while. I just reset the computer and it stopped bouncing.
Just take the positive leads off your battery for 3+ hours. Then hook it back up.

Kyrol · 02-05-2003, 01:20 AM

I know its apples to oranges but my rx7 did that and it was a bad TPS. hope it helps some.

C B · 02-05-2003, 03:56 AM

matt golin:

To reset your computer you:

1. Disconect NEGATIVE terminal

2. Let sit for 15 seconds

3. touch your private area repeatedly.

BV1 · 02-09-2003, 04:53 PM

Sounds like a MAF problem to me, install a CAI recently, did you put the MAF in the right way?

-Steve

sage020 · 02-11-2003, 07:44 PM

The car won't start at all anymore just cranks but never fires. Ive had the cai for prob 6 months and never had a problem. This might be a shot in the dark but when the weather gets better im gonna try and check the timing belt. I think if I last some teeth on the belt it could mean major problems. I still wanna check the plugs and wires also. I hate to be driving the supra in the snow so hopefully Ill find the problem soon.

donchichi · 02-16-2003, 01:38 AM

ok I had similar symptoms with my scoupe 92. Resetting the computer works.... for a while then it starts again. However after my speedometer went blip, I changed the wire and it works fine. But then after a few months it started up again but this time randomly. I don't have the jumping rev meter but I have random loss of power and misfiring not at close intervals, it'll happen once a week or so when engines hot or cold then as mysteriously as it came it'll go away. It's weird cause I've gotten a few mechanics to look at it and all were baffled, they've even tried changing the spark plugs, spark plug wires, idle timing... but it happens randomly.

I also suspect my rear fuel pump as my fuel meter goes below E when full and when its half full it'll go up to slightly above E and drop accordingly. I'm thinking of changing my spark plug cables, remove the catalyctic thingy to see if there's any changes. This will only be done at the end of the month though.