The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support STM Tuned
Please Support Rix Racing

2G bogging/hesitation/fuel cut-low rpm's only

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

cadilacmike

Probationary Member
28
0
Jun 17, 2013
tuttle, Oklahoma
Ok, I'll try my best to explain this. On first start up is when its worse, at idle or driving. If i rev it up it cuts out and bogs down between 500-1800 rpms, same with driving on take off, it stalls at first then starts bogging down. If yo put the gas down further it will eventually back fire. with that said it will fight through and then drive fine the rest of the way.

A little background:

car sat a while, ran gas out and now on 4th tank
new plugs gaped.028
new fuel filter
new alternator
new battery

It has stock injectors, not sure about pump it is extremely loud though
afpr
16g with maft W/gm maf

That's what i know of and as far as I've gotten so far
 
If you literally ran the car out of gas before it sat, you may have pick up some sediment from the bottom of the tank. If that is the case change the fuel filter, and have the injectors flow tested.

Sorry didn't see where you changed the fuel filter.
 
No I bought it from a guy he said he had been sitting 6 months, i suspect longer though, then ran it low not out (sorry) then ran 4 more tanks of 91.
 
Car sat a while maybe a hose cracked or something from dry rot.

1. Vacuum leak. Spray some carb cleaner around and see if the idle changes. Especially around the injectors.#
2. Make sure the sensor on the back of the throttle body is not loose.
3. Maybe loose connection at the MAF
4. Missrouted vacum lines
5. If you have one, check to make sure the Egr valve is functioning properly.
 
Vacuum lines are right
got egr block off
I have replace the vacuums lines i notice that looked bad.

I will check the other stuff tomorrow, it does look to have a 1g intake, throttle body and camshaft position sensor, don't know if that helps.

Also it does not have stock intake, looks home made from exhaust pipe and it sits on waste gate actuator nipple valve that stands strait up on the big 16g and bends the vacuum hose how do you other guys running that turbo with after market intake get around that.

Thanks for the input.
 
Uh, yea forgot about that, it has one for o2 and knock sensor. How many o2's supposed to be on these,I got three, the one by the manifolds has cut wires hanging out, maybe someone had wide band hell I don't know too much about these. I'm taking it tomorrow to the only descent shop here in Oklahoma I've heard of
 
Ok, took it to the shop, found someone did a 6 bolt swap before me. Went for a test drive he said felt like knock sensor, changed it today(big pain in ass)still doing same, don't know if i got it tight enough or not enough. Back to the drawing board, any suggestions?
 
Ok seems to be getting worse, today it is acting all kinds of nuts. Hard to explain but here goes:

First start up, if you rev it slowly or full rev its cuts out still until it breaks the 2k rpm range.

Pretty much the same while driving, except now its bogging down worse when given gas at any speed. Give it gas it bogs down, give more gas it tries to fight through, kind of bucks back and forth trying to get speed. Put throttle down half way or more it gives it the ol pull back like its gonna kick it in the ass and go, then just stops at the kick back and actually slows down,then eventually backfires.

Its really hard to explain hope that's clear enough. If there is anyone in the Oklahoma area that can look at it and help me out, I don't mind driving.
 
If there are three O2 sensors in the exhaust system then one is from a wideband that was installed at some point. The one that really matters is the upstream (front) O2 sensor. The only real function the downstream (rear) O2 has is to check and see if the catalytic converter is working. Find out if the CEL is for the front or rear O2.

The first thing is, has the car ever ran right since you've owned it? If yes, then ask yourself what could have possibly changed to bring you to where you are. If there are no obvious answers, start from the beginning...

Since you can't even accelerate slowly without bucking, backfiring, etc, this doesn't sound like a boost leak issue, but the idea here is to root cause the issue by going through each system from (more or less) most basic to most complex, so you should still look into that and everything else. Just go through everything one piece at a time.

If you've never done a boost leak test before, there are lots of threads out there that explain how its done, and also YouTube videos.

https://www.youtube.com/watch?v=u3Kqh52PC6Q

https://www.youtube.com/watch?v=fdjadhUP1u4

https://www.youtube.com/watch?v=Uq2o_6pPpBw

https://www.youtube.com/watch?v=cZwopj9_Y4o

Look over everything and make sure it is all put together properly. Did someone try to do some kind of janky FIAV blockoff? Or is there no block off and no coolant lines routed to the throttle body? Is your EGR valve just blocked off, or is the whole system removed? If it's all still in there, remove it all to simplify things.

http://www.dsmtuners.com/forums/152217692-post10.html

Do you have fluid leaks? If so, fix them.

Next, start with ignition. Check the coil pack, PTU, spark plug wires, double check plugs, and check the wiring in between everything.

Coil Pack testing:
http://www.dsmtuners.com/forums/attachment.php?attachmentid=33471&d=1088544507

Power transistor testing:
http://www.dsmtuners.com/forums/articles-electrical-wiring/229419-how-test-power-transistors.html

1g CAS testing:
http://www.dsmtuners.com/forums/152299200-post2.html

2g CAS and CPS testing:
http://www.dsmtuners.com/forums/152302942-post5.html

And really, just read this:
http://www.dsmtuners.com/forums/152649702-post2.html

Check the fuel system. Are all the injectors working properly? What does the wiring to them look like? You changed the fuel filter, so you're good there. It might be worth it to check the filter on the fuel pump.

Then start checking all the sensors (ISC, TPS, CPS, O2, Knock, clean and check the MAF), look through all your fuses and relays, and really you should just check anything that can be adjusted (BISS, Throttle, etc.), period.

A Digital Multimeter and factory service manual should be your best friends.

Here, this might also help.

https://www.youtube.com/watch?v=TccGNg-vb8g

https://www.youtube.com/watch?v=EBM3bHCqrN8

https://www.youtube.com/watch?v=Ng6llVYSq4w

I realize that not all of this is going to be relevant to your specific issue, but lets face it, when a car is acting the way that yours is, it probably needs a tune up and at the very least a complete once over. When you are approaching a problem like this and have no idea what it is, jumping around to random things only solves the problem through luck. Approach it systematically, root cause the issue.
 
If there was a wideband installed and the wires are just cut.. perhaps he was using the wideband to log with while using it as a Narrowband sim.. so when the wires were cut, the ECU now doesn't know how much fuel/air to throw in there because it's running blind.. are there any codes?


EDIT: That might be phrased a little off, but hopefully the more experienced know what I'm trying to get at and can help my wording.
 
If there was a wideband installed and the wires are just cut.. perhaps he was using the wideband to log with while using it as a Narrowband sim.. so when the wires were cut, the ECU now doesn't know how much fuel/air to throw in there because it's running blind.. are there any codes?


EDIT: That might be phrased a little off, but hopefully the more experienced know what I'm trying to get at and can help my wording.

This is the main reason I asked if the car had ever ran correctly while he's owned it. By the way he has described things, it sounds like he never cut any wires to an O2 sensor, so I don't suspect this is the problem.

He also mentioned he had codes from an O2 sensor and also the knock sensor, he went ahead and replaced the knock sensor.
 
This is the main reason I asked if the car had ever ran correctly while he's owned it. By the way he has described things, it sounds like he never cut any wires to an O2 sensor, so I don't suspect this is the problem.

He also mentioned he had codes from an O2 sensor and also the knock sensor, he went ahead and replaced the knock sensor.

He actually did say that there were wires cut from one of the sensors.. if he has a code for an O2 sensor then it very well could be the problem.

Uh, yea forgot about that, it has one for o2 and knock sensor. How many o2's supposed to be on these,I got three, the one by the manifolds has cut wires hanging out, maybe someone had wide band hell I don't know too much about these. I'm taking it tomorrow to the only descent shop here in Oklahoma I've heard of


Which is the one the ECU uses to tell Air/Fuel.. so it would make sense that it would run horribly because it would just dump fuel. Does that reasoning make sense? I'm also learning so I don't want to misdiagnose something..
 
He actually did say that there were wires cut from one of the sensors.. if he has a code for an O2 sensor then it very well could be the problem.

Which is the one the ECU uses to tell Air/Fuel.. so it would make sense that it would run horribly because it would just dump fuel. Does that reasoning make sense? I'm also learning so I don't want to misdiagnose something..

He said there were wires cut, but he didn't say that he cut them. Again, that's why I asked if the car ever ran correctly since he owned it. If the wires were always cut and the car ran in an acceptable manner at some point while they were cut, then that is likely not the major problem. He also didn't indicate if the CEL was for the front or rear O2 sensor and I don't take vague descriptions of location very seriously. If he said, "I accidentally broke the O2 sensor wires connected to the O2 sensor located on the O2 housing" or "the wires connecting to the upstream O2 sensor are melted in half" that would be different. There could be a wideband O2 sensor in the wrong spot right below the turbo on the downpipe, I have no idea, I'm just trying to teach this dsm guy how to diagnose his car problems.

But you're right, if it is in fact the upstream O2 sensor with damaged wires, that should be top of his list to fix.
 
OK:

The car has never ran correctly since I've owned it.

The main O2 sensor was cut not by me, but I'm guessing it went bad and they couldn't get it out, so they welded another on the exhaust.

When I changed the knock sensor, the O2 CEL went off. The only CEL I have now is P0443.

IT has egr block off and looks like all emissions related stuff removed.

Disconnected the TPS, seemed to be the same.

I did find a couple loose bolts connected fuel line the fuel rail tightened them, adjusted fuel pressure to 43.5 (looked to be about 41 before) and tightened the vacuum hoses on the AFPR, seems better on idle, haven't driven yet.
Next I was gonna replace the plug wires and thought it might have something to do with coil so I'll check that to.

Next Question is, on the 2g the TPS sensor is mounted on the intake but not on 1g nor mine, it is however hanging behind intake with a vacuum line going to a T with vacuum going to line on the back of the intake. Is that correct?

Thanks for all the replies and help really appreciate since closest shop is 30-45 minutes away and don't want to drive there every day.
 
OK:

The car has never ran correctly since I've owned it.

The main O2 sensor was cut not by me, but I'm guessing it went bad and they couldn't get it out, so they welded another on the exhaust.

When I changed the knock sensor, the O2 CEL went off. The only CEL I have now is P0443.

IT has egr block off and looks like all emissions related stuff removed.

Disconnected the TPS, seemed to be the same.

I did find a couple loose bolts connected fuel line the fuel rail tightened them, adjusted fuel pressure to 43.5 (looked to be about 41 before) and tightened the vacuum hoses on the AFPR, seems better on idle, haven't driven yet.
Next I was gonna replace the plug wires and thought it might have something to do with coil so I'll check that to.

Next Question is, on the 2g the TPS sensor is mounted on the intake but not on 1g nor mine, it is however hanging behind intake with a vacuum line going to a T with vacuum going to line on the back of the intake. Is that correct?

Thanks for all the replies and help really appreciate since closest shop is 30-45 minutes away and don't want to drive there every day.

If the car has always been like this, then verify that the extra O2 sensor you've described is plugged into the factory harness. Next, get an O2 sensor socket, let the car warm up to operating temperature, turn it off, remove the old O2 sensor, put the new one in the correct position, and plug the extra bung welded to your exhaust.

P0443 can be caused by the gas cap being loose. Is the vent line from your gas tank capped off? It should be left open for an EGR/EVAP delete.

The TPS, Throttle Position Sensor, is mounted on the forward facing side of the throttle body on both 1G and 2G. Are you referring to a MDP sensor maybe? A photo would help in this case. Where does the other end of the T go on the sensor you're describing?
 
If the car has always been like this, then verify that the extra O2 sensor you've described is plugged into the factory harness. Next, get an O2 sensor socket, let the car warm up to operating temperature, turn it off, remove the old O2 sensor, put the new one in the correct position, and plug the extra bung welded to your exhaust.

P0443 can be caused by the gas cap being loose. Is the vent line from your gas tank capped off? It should be left open for an EGR/EVAP delete.

The TPS, Throttle Position Sensor, is mounted on the forward facing side of the throttle body on both 1G and 2G. Are you referring to a MAP sensor maybe? A photo would help in this case. Where does the other end of the T go on the sensor you're describing?

As stated sounds like an O2 sensor problem.. make sure you do the above.
 
Your right I said that wrong, meant MDP sensor. Ill post a couple pics in a minute soon as I can get it on computer.

One end of the T goes into back of intake manifold, the other into the brake booster. I think that's what it is.

I do have a lot of black oily gunk, looks to be coming from under my CAS, it's everywhere under it.
 
Your right I said that wrong, meant MDP sensor. Ill post a couple pics in a minute soon as I can get it on computer.

One end of the T goes into back of intake manifold, the other into the brake booster. I think that's what it is.

I do have a lot of black oily gunk, looks to be coming from under my CAS, it's everywhere under it.

Sounds like you might be describing the sending unit for an electronic boost gauge that is T'd into the brake booster line. I'm not a huge fan of T'ing into anything for a boost/vacuum source.

As far as the black gunk is concerned, you'll just have to find the source of it. Could be an oil leak from the back of the valve cover.

EDIT: I forgot you have a 6 bolt swap for a second. If you are running a 1g intake manifold, there is no place on there for a MDP sensor like on a 2g, so it's likely whoever did your swap T'd into the brake booster line for the MDP sensor. Something to consider would be sourcing a new brake booster line and drilling/tapping your intake manifold and running a line from there to a vacuum distribution block. Then buy the JMFAB MDP sensor relocate fitting and use that off your distribution block, this would be cleaner and allow you to discontinue the use of T's.
 
Here are a couple of pictures, the small vacuum is running to the back of the MDP sensor. If that's in the wrong spot can I just cap it then?

Here is the MDP
 

Attachments

  • CAM00044.jpg
    CAM00044.jpg
    49.6 KB · Views: 189
  • Screenshot_2013-06-29-19-05-42.jpg
    Screenshot_2013-06-29-19-05-42.jpg
    37.7 KB · Views: 157
  • CAM00045.jpg
    CAM00045.jpg
    41.5 KB · Views: 198
Here are a couple of pictures, the small vacuum is running to the back of the MDP sensor. If that's in the wrong spot can I just cap it then?

Here is the MDP

The way it is now will technically work, it's just not a preferred method in my opinion.
 
OK then I guess I'll start going down the list.

Appreciate the help so far.
 
Last edited:
Well I took the injectors out and the O-rings were pretty rough, one was cracked in half, guess I'll order new ones and see if that does anything.
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top