4g61t.org

I have an 89 4g63 colt. It has been running great until recently. When I first start the car and drive it, it has no problems. Normally once it's warmed up it will lose all power. If I give it less than 10% gas the car will run and drive but obviously not accelerate well or really be tolerable. If I give it more gas than that I get maybe some bucking for a half a second and then 0 response. It's like the gas pedal does not exist. Now if I shut it off and restart it right away, it sometimes will run fine, but most of the time it'll continue having the same issue. Any ideas? It kind of seems like it's fuel related but I've never had a pump work only half the time.

No CEL on the cluster?

Try disconnecting your MAF and see what happens.

^^^ Definitely sounds like MAF or a boost leak.

_________________
Thom
1991 GVR4 1025/2000 (PTE 1200's, 16g, DSMLink v3, gm-maf, eagle/ross, .020 over, 272's, EVO VIII Wheels)
1992 GVR4 866/1000 (getting everything from above)

I'll give the MAF a try tomorrow when I have time to drive it. Thanks for the tip, I didn't think about that.

Maf, massive boost leak like a blown ic boot, TPS going bad when it gets hot. Check the TPS voltage swing when it's nice and hot.

_________________
'89 Colt GT w/bigger than stock turbo
'91 Talon AWD w/bigger than stock turbo
'05 Dodge diesel w/bigger than stock turbo

80% sure that could be the MAF, It happened to me in the same way time to upgrade to the 2g maf

_________________
91' Mitsubishi Colt 4G67T FWD "The Minion" - 12.26@118
94' Mitsubishi Galant GS 4g63 Swap "White Unicorn"
95' Eagle Talon Tsi FWD "Ernie's car" - 13.92@104 *Rest In Parts*

I tried to take a video of it but it's not exactly clear what the issue is in it. At around 5 second I floor the vehicle and it goes into what I call Decel mode. It's literally like the car starts deceling when I floor it or go above 5% throttle.
I replaced the MAF and thought it fixed it but I was wrong. My Tach does not work in the video by the way.
http://youtu.be/LMjB_JSd5y0

Take a look at the TPS also, seems you car is cutting the fuel when you get in the gas. Also, are you runng 5 Wally's?? That fuel pump is way loud. I can barely hear mine in my colt.

_________________
Thom
1991 GVR4 1025/2000 (PTE 1200's, 16g, DSMLink v3, gm-maf, eagle/ross, .020 over, 272's, EVO VIII Wheels)
1992 GVR4 866/1000 (getting everything from above)

I will check out the TPS tonight, I can't test it but I can replace it with a known good unit.
The fuel pump was in the car when I purchased it. It is a loud SOB. I plan on swapping it with my spare Walbro.

How is your timing? Knock sensor oozing it's guts out?

_________________
Had a:
1991 Eagle Summit ES Hatchback - 4g15 12v 5spd
1991 Dodge Colt -4g15 12v 4spd
Have a:
1978 Oldsmobile Cutlass - 468BBO TH350
Round 3:
1990 Dodge Colt-4G63T 5spd

It's on factory timing and factory boost. The engine itself has fairly low miles, probably around 2000 right now with all fresh components. I don't have a wideband in it right and I'm honestly not sure if the CEL even works. I'm waiting a few more weeks to order DSMLink which I know would help resolve this even faster. I'm just attempting to troubleshoot prior to the installation.
I bought the car for extremely cheap as a project and I'm trying to slowly put money in it rather than throw money at all the problems and hope they get resolved.

I replaced the TPS sensor to no luck. Still the same problem. I have noticed if I shut the vehicle off and then re-start it, it will run fine for a while until it starts repeating the symptoms. Any other ideas?

Do you have a logger? You can easily check your timing and knock count then. It almost sounds like your cas is off a little causing it to mess with timing and knocking which cuts it back even further.

_________________
Had a:
1991 Eagle Summit ES Hatchback - 4g15 12v 5spd
1991 Dodge Colt -4g15 12v 4spd
Have a:
1978 Oldsmobile Cutlass - 468BBO TH350
Round 3:
1990 Dodge Colt-4G63T 5spd

I don't currently have a logger but it's in time and I'm not sure that the knock sensor would only be faulty after the driving the vehicle for a period of time.

It sounds like it's running fine in closed loop and then once it switches to open loop and takes in sensor data, it falls on it's face. This leads me to believe that it's sensor related and the knock sensor dying would give the symptoms you've described. A lot of the times, usage doesn't determine knock sensor life, how long ago it was made determines that.

_________________
Had a:
1991 Eagle Summit ES Hatchback - 4g15 12v 5spd
1991 Dodge Colt -4g15 12v 4spd
Have a:
1978 Oldsmobile Cutlass - 468BBO TH350
Round 3:
1990 Dodge Colt-4G63T 5spd