Mitsubishi Eclipse 4G Forums banner
1 - 17 of 17 Posts

·
Registered
Joined
·
46 Posts
Discussion Starter · #1 ·
2007 eclipse gs 2.4. 188k The car is hard to start , misfiring rpms fluctuating. I can baby the gas and after about 4 minutes will settle out then It will run and start good all day till the next morning I have replace many parts , it keeps throwing p421 p431 codes. I have replaced all o2 sensors coils, spark plugs, coolant temp sensor ,maf new timing belt and sensor Could my cat be causing this?
 

·
Moderator
Joined
·
2,891 Posts
For sure, especially at that mileage

I would advise not to keep running the engine with them clogged up, it's very bad for the engine to have all that backpressure with nowhere to go, the cats can even break up and get sucked back into the engine, then you'll have major problems

Take the header off and get a crow bar
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #3 ·
Thank you, I will take it off this weekend. Will the o2 sensors read ok and everything run fine being gutted?
 

·
Moderator
Joined
·
2,891 Posts
Thank you, I will take it off this weekend. Will the o2 sensors read ok and everything run fine being gutted?
You'll still have the same cat codes, because without cats the ECU will think that they are bad and passing too much exhaust, but at least you won't damage or blow up your engine from a clogged exhaust
O2 sensor spacers (spark plug anti foulers) can work intermittently to keep the codes away, otherwise the Fastworks tune is required to trick the ECU not to pop those codes anymore
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #5 ·
I took cats off and gutted them one side had already started to collapse. Got it all back together and after driving it about 40 miles it runs fine

Got up this morning and it still very hard to start, sputtering and spitting. You have to try 5 or six times feathering the gas. I finally let it sit with key in on position but not running and it started better

Do these cars have fuel pressure regulators? The fuel pump was changed a few months ago trying to fix this problem. If it sits overnight it is hard to get it running, once you do it’s good all day.
 

·
Moderator
Joined
·
2,891 Posts
I took cats off and gutted them one side had already started to collapse. Got it all back together and after driving it about 40 miles it runs fine

Got up this morning and it still very hard to start, sputtering and spitting. You have to try 5 or six times feathering the gas. I finally let it sit with key in on position but not running and it started better

Do these cars have fuel pressure regulators? The fuel pump was changed a few months ago trying to fix this problem. If it sits overnight it is hard to get it running, once you do it’s good all day.
I believe the pressure regulator is just apart of the whole fuel pump assembly with the pump under the rear seat
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #7 ·
New fuel pump two months ago, it’s like the fuel pressure leaking down overnight. Bad injectors. O rings.
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #8 ·
if I was to spray starting fluid it it stars right up that would be indicate a fuel pressure problem right ?
 

·
Moderator
Joined
·
2,891 Posts
if I was to spray starting fluid it it stars right up that would be indicate a fuel pressure problem right ?
Yeah probably
It’s not recommended to spray starting fluid on a fuel injected car
You might have leaky injectors

the problem is that this car doesn’t prime the fuel pump prior to engine cranking, it only starts pumping the fuel pump once the engine is cranking

my WRX will prime up the fuel pump for a few seconds right when you turn the key on
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #10 ·
Im going to buy some injectors, what do you recommend and where ? I have been buying parts from rock auto , also what about a bad egr? Would this cause this extreme hard start in the morning?
 

·
Registered
Joined
·
1 Posts
I am having a similar problem i have replaced the spark plugs, air filter, o2 sensors, cats, seals and still have p0431 and p0421, and recently my car started stalling warm at lights if not reved, i have a guess that the egr valve might be a culprit so i will replace it, if its not it, it might be faulty cats will post when i fix it for anyone in the future who encounters this problem
 

·
Registered
Joined
·
4 Posts
Has anybody solved this problem? I’m having the same issues with my 07 GT 203k miles. Already replaces all plugs boots, MAF, upstream O2s and nothing is better and she is dumping fuel at idle
 

·
Basically Stock
2009 GS Turbo. 2007 GT
Joined
·
6,658 Posts
Has anybody solved this problem? I’m having the same issues with my 07 GT 203k miles. Already replaces all plugs boots, MAF, upstream O2s and nothing is better and she is dumping fuel at idle
At idle you have high manifold vacuum, and the exhaust has higher than atmospheric pressure. An EGR valve leak would allow deoxiginated air to enter back in at an uncontrolled rate, causing an overly rich condition and difficult idle. Before buying a new one, note two things. You can clean them, and I have a collection of them and can sell one cheap should yours be damaged (OEM they're quite expensive). Cleaning your EGR valve is a normal thing, especially at such mileage.

MAF or O2 issues would be seen through live data testing (the tool is cheaper than buying a new MAF and O2 sensors). Spark plug tube seals (plug boot?) would be bad if your plugs were oily, ignition coils (plug boot?) wouldn't all die at once, plus you'd be chasing a single cylinder misfire. The 4G doesn't have plug wires like a classic distributor type system does, so doesn't have plug boots. I am entirely guessing which part you mean there.
 

·
Registered
Joined
·
4 Posts
At idle you have high manifold vacuum, and the exhaust has higher than atmospheric pressure. An EGR valve leak would allow deoxiginated air to enter back in at an uncontrolled rate, causing an overly rich condition and difficult idle. Before buying a new one, note two things. You can clean them, and I have a collection of them and can sell one cheap should yours be damaged (OEM they're quite expensive). Cleaning your EGR valve is a normal thing, especially at such mileage.

MAF or O2 issues would be seen through live data testing (the tool is cheaper than buying a new MAF and O2 sensors). Spark plug tube seals (plug boot?) would be bad if your plugs were oily, ignition coils (plug boot?) wouldn't all die at once, plus you'd be chasing a single cylinder misfire. The 4G doesn't have plug wires like a classic distributor type system does, so doesn't have plug boots. I am entirely guessing which part you mean there.
I removed the egr and cleaned it up, vacuum tested it, it seals properly and I can hear the stepper motor function as it should as soon as the key is in the on position. A few weeks before this happened I changed the plugs and coil pack boots(the rubber end of the coil pack that slides over the spark plug itself) as well as the contact springs inside them as routine maintenance. The plugs are ruthenium from rock auto for our cars.

I originally thought the problem was an evap leak because I had the code for it for years with no problems so I figured I’d start there. The leak was on the vent tube that’s welded to the tank. I have since tested the evap system and tank, there are no leaks now and I can’t get the code to come back so I’m assuming that it wasn’t the main problem.
Everything reads normal for the most part during live data minis my o2 sensors voltages. The only codes I have now are p0302 and p0157. The anti skid lights come on after a little driving.
 

·
Registered
Joined
·
4 Posts
I’ve swapped plugs and coils, no difference. Could it be a stuck injector? Ive tested their ohms they all test normal.

update: I took the plenum back off. All of the cylinders had a thin layer of moist oil/recycled carbon from the exhaust except cylinder 2, it was dry.
 
1 - 17 of 17 Posts
Top