420A 420a not idling right cannot figure out why!

[BorinquenEclips]

Ok so I have a 99 Eclipse RS currently as my daily until I build my GSX. About a year ago I removed the motor because of a terrible oil leak that I just couldn't figure out so I ended up changing every gasket on the car just to make sure it wouldn't come back.

Now when I put the motor back in and started it up it started to idle fine but as soon as the motor warmed up it started to idle like a cammed out V8. I figured it was a vacuum leak so I check every vacuum line there is and none of them have a hole or tear or anything that would cause a leak.

So I took it to autozone to hook the computer up to it to see if any codes were thrown and it said my EGR and TPS were bad. Well I assumed the TPS sensor would be the problem, but after replacing it, the car still idles like a bridge ported rotary engine. I wouldn't imagine the EGR would affect the idle but maybe one of you guys can prove me wrong.

I was fine with ignoring it for a while but now it is just plain annoying since it sometimes even wants to die if I tap the gas on a hill or with the air conditioner on. I would love it if it were cammed out but its not and would love to figure out the problem. Thanks in advance.

Oh and one more thing, I did do some porting with a dremel to the intake manifold only, not the head, and I have my dad telling me that the porting is whats causing my idle problem. I think he's wrong but i don't know its a thought. What do you guys think?

 

[1995gsx20g]

i know its a N/T but do a BLT with like 1psi to check for vacuum leaks.

 

[dalesmitsu]

Have you tested your IAC, it could going out. That oil leak could be the lower passenger side of the head. There's information how to correction at 2gnt.com

 

[slow8033]

I know this sounds crazy...but check your coolant levels, and burp the system. Get any and all air bubbles out of it. The 420a reacts HORRIBLY to the slightest amount of air in the cooling system. Had the same problem, car wouldnt run for $#%. It had a really low loppy weak idle. Under any type of load it would die. I would push in the clutch at a stop, and It just died. I changed IAC, tons of other things, tore it apart. I switched injectors, even took it to a shop when I ran out of ideas...they had it for 4 days and couldn't find a thing wrong with it.

I finally got so pissed off I was taking it to mitsubishi, I pulled into the lot and slammed on the breaks to park it. That sudden lurch caused the car to run perfectly. Has ever since.

Elevate the front of the car about 6" to a foot, open the radiator cap, start the car, let it warm up. You will probably start to see bubbles begin circulating out of the system. Get it good and full, and make sure there is NO air in it whatsoever.

could be a free fix.

 

[david-b]

I've never heard of the coolant causing problems. Technically you can run cars without coolant, so not seeing how that really makes sense.

Have you done a compression test to make sure the timing is dead on?

 

[hoyboi]

just to go off slow8033 i had air in my coolant lines when i had a 420a and it did the same thing but i fixed the coolant leak and refilled it and it ran perfect

 

[Develop247]

i'm sure you checked your trusty dsm bible for the possible reasons, but if not here it is for you.
vacuum leak (you knew this possibility), leaking egr valve, spark plugs fouled, air filter clogged, fuel pump not delivering enough fuel, leaking head gasket, timing belt and/or pulleys worn, camshaft lobes worn. the connectors for the two sensors that came up on the cel scan; can they be interchanged? maybe they were swapped? I know from my old honda, sensors used the same connectors. as far as your mod to the manifold, i don't see it making the difference unless you went a little crazy porting it. . Good luck and at least your car runs! p.s. are you using an safc?

 

[slow8033]

Yeah, I told you It sounds crazy at first read about the coolant having air in it...But I have seen it in my car, and in other's cars personally. It must disrupt a signal from a sensor that causes the computer to get a false reading and in turn the car runs like crap.

Im not saying it's for sure the problem, but it is a known issue, and worth checking out.

 

[pgarland]

The EGR can definitely affect the motor at idle. It is supposed to be closed at idle, so if it is faulty and is actually open at idle (a filthy EGR can cause this to happen), it'll act like a huge vacuum leak, and cause some of the issues you mentioned. Far too many times on these forums I have seen guys thoroughly clean or replace (or block off) their EGRs and their idle issues clear up immediately. I know when I got my DSM, I had idle issues, and cleaning the EGR, throttle body, and intake manifold solved my problems. Nothing wrong with taking it off and spraying a whole can of carb cleaner into it, but be prepared to see a ton of sludge come out!

 

[Redrum_8247]

I know this sounds crazy...but check your coolant levels, and burp the system. Get any and all air bubbles out of it. The 420a reacts HORRIBLY to the slightest amount of air in the cooling system. Had the same problem, car wouldnt run for $#%. It had a really low loppy weak idle. Under any type of load it would die. I would push in the clutch at a stop, and It just died. I changed IAC, tons of other things, tore it apart. I switched injectors, even took it to a shop when I ran out of ideas...they had it for 4 days and couldn't find a thing wrong with it.

I finally got so pissed off I was taking it to mitsubishi, I pulled into the lot and slammed on the breaks to park it. That sudden lurch caused the car to run perfectly. Has ever since.

Elevate the front of the car about 6" to a foot, open the radiator cap, start the car, let it warm up. You will probably start to see bubbles begin circulating out of the system. Get it good and full, and make sure there is NO air in it whatsoever.

could be a free fix.

This is everything my 98 420a is doin. And I replaced the radiator before I even drove the thing when I first bought a couple months ago. For sure gonna try this n I'll get back ith an update.