Running super rich after swap.

[Laservision90]

So I just completed an engine swap from a time jumped 4g63 to a running one. I pulled the whole motor out, transferred everything to the new long block and put the motor back in. The car that I put it back into was a stunningly clean Plymouth laser fwd turbo, oil cooled and driven by an old man until the timing jumped. Because I'm from Wisconsin and the car has no rust I decided that it would be worth picking it up for scrap and putting a new engine into it. Well I put the new engine in it, all new timing components, after pump, and all that, then I started to do the classic swap cycles, "test run, fix, repeat." Well the car has normal power and acceleration until 3000 rpm. But as soon as it hits about 3.5 it stumbles and blows smoke (obviously running really rich) I took the set of plugs out and I put new ones in and took it for a five mile drive. When I pulled the plugs out to check them, they were coated with black soot. (Obviously fuel) there are no check engine lights on in the car, (but it is obd I so....I'm not sure). My question is where would any of you start looking for a fuel problem? Because I've never seen a motor DUMP this much fuel into a motor after a swap.

Thanks for all the help in advance.

 

[infaroot]

I would say look for a boost leak

 

[oittehgaps]

I start by pulling the plugs to make sure all four cylinders are firing, and verify the ignition timing, and firing order.

Did you do a compression test as well?

 

[wparks]

I assume the smoke was blue/black (not white) and the plugs were a dry black (soot for sure) and not oily? The engine that went in is from the same type (turbo, manual) of car right? (same 450cc low resistance injectors with dropping resistor, etc). If the injectors are correct, (and the fuel pressure regulator is working) (did you change the PCV?) then I agree- it almost has to be a boost leak, that is causing the rich condition only when there is enough pressure to leak air. Double check everything in that path, and if you still can't find it do the leak test. (which is a great idea either way).

 

[chris00326]

I had kinda the same problem on my 91 gst and it turned out to be the mass air sensor. especially if the car was sitting in the elements for any amount of time. it wont always throw a code either. check it by unplugging it and seeing if it stops dumping fuel under load. you can also try and change it for a known good one.

 

[oittehgaps]

If you unplug the MAF it will barely run, if at all. I know if my MAP sensor isn't plugged in the car won't start at all but it will blow a shit load of black smoke.

You can also check the coolant temp sensor/ wiring. It locks at something like -63 degrees if the wiring is messed up, and it will run like crap.

 

[chris00326]

If you unplug the MAF it will barely run, if at all. I know if my MAP sensor isn't plugged in the car won't start at all but it will blow a shit load of black smoke.

You can also check the coolant temp sensor/ wiring. It locks at something like -63 degrees if the wiring is messed up, and it will run like crap.

Thats not actually true. if you unplug the map it sends the computer into kind of a limp mode and make the car run on set values without the ability to compensate. when mine went out it dumped massive fuel cus it was reading wot of air at all times. i unplugged it and it actually ran better. granted it had idle surge but i was actually able to drive it without raw fuel running out of the exhaust.

 

[oittehgaps]

Thats not actually true. if you unplug the map it sends the computer into kind of a limp mode and make the car run on set values without the ability to compensate. when mine went out it dumped massive fuel cus it was reading wot of air at all times. i unplugged it and it actually ran better. granted it had idle surge but i was actually able to drive it without raw fuel running out of the exhaust.

That's not actually true. If my MAP sensor is unplugged the car will not start.

Of course I'm on speed density, and your driving around with your sensors unplugged idle surging.

 

[chris00326]

Speed density and stock mass air are different. I only drove it that way for a day and it pinpointed the problem. Your car wont start because its a differnt system. like i said before unplugging it puts it in limp mode. it is asafty feature witch alows the car to run albiet poorly. Also it is a good place to start if the car is dumping fuel at any rpm range because of the simplicity of the check.

 

[oittehgaps]

Thats not actually true. if you unplug the map it sends the computer into kind of a limp mode

You said MAP sensor not MAF.

 

[chris00326]

Youre right i meant maf not map

 

[oittehgaps]

No big deal. Now I know what you were talking about.

Like we were saying a bad MAF or MAP can cause a rich condition.

 

[Laservision90]

The motor is out of the same kind of car, turbo, manual, just a gsx, not a fwd. that won't matter though because I got the motor S a long lock and transferred everything over, including the oil filter housing so that I can route the stock oil cooler. Compression tested correct and the plugs are sooty and powdery, consistent with running rich, all four cylinders are running and firing and all four plugs that I pulled out were the same symptoms. The car idles very low and doesn't idle at all with the mass air flow unplugged but will start and run. I drove it about 20 miles today (not just up N down the road) and after that it acted just normal. But after I let it sit for a half hour it did the same thing. (Loss of power when you put the gas pedal more than 1/4 of the way down and loss of power at 3000 rpm. I think I'm gonna pull the throttle body apart and clean all of the sensors and such. I heard that could be the issue, but if anyone else has any ideas.

Ps. Boost is exactly where it supposed to be, I think that it just dumps to much fuel into the motor that it can't help but cut. At first I thought it was fuel cutting but Fter seeing the black smoke, it can only be to much fuel. Kinda concerned that ill end p clogging a cat trying to figure this issue out if it isn't already clogged.

Btw the car is either obd1 or 0? I'm not sure, and can't seem to find a connector for it to hook up to my scanner :/.

 

[chris00326]

unless your check engine light is on your not going to be able to get anything from a scan. It has to do with the ecu reading to much air and is compensateing by dumping fuel. Is your fuel pump, injectors, and fpr all stock?

 

[Laservision90]

The whole car is stock, not even a cai. I was gonna start messing its it after I completed everything and got the car running somewhat reliable, or I was gonna sell it. I'm thinking it has to do with the iac or the maf. The car actually runs better when you unplug the bypass hose, creating the vacuum leak and that bypasses the air filter giving the car more air to run on. But it still fuel cuts, just instead of fuel cutting at 3 grand it does it at 3.5.

 

[chris00326]

Try getting some MAF cleaner and clean the MAF. its like $7.00 at autozone. also it wouldnt hurt but run some seafoam trough it to help clean out the fuel system.

 

[Supra Mario]

Is everything exhaust related good? i had a bad cat/leak and it threw off my o2 sensors off and got 10 mpg , did a boost leak test yesterday and still cant find the problem. Good Luck !

 

[Laservision90]

Already cleaned the maf. Cleaned the boost control solenoid too. I'm running out of sensors to clean. What really got me is how it ran good after I drove it for a while (20 miles) but then gave me the same symptoms after I shut it off for a couple minutes.

 

[chris00326]

Try swapping out MAF for a known good one. check Fuel pressure regulator and do a boost leak test. Also did you replace fuel filter. if not pull it out and try and blow trough it. it you get resistance replace it.

 

[Laservision90]

The fuel pressure regulator would make sense, so would the maf, but I don't see how running rich would be connected to a fuel filter unless there wasn't one to manage resistance.

 

[chris00326]

I say fuel filter because its cheap and easy to check. it could cause a rich condition by not allowing a consistant flow causing the computer to possibly over compinsate and force fuel. just a theory but it makes sence to me .

 

[Laservision90]

Why would it run good when I drove it for a while then?

 

[Laservision90]

Update. Almost positive that the catalytic converter is clogged and that is what is causing my problem. After running the car at night for the first time really, I looked under the car as a hunch and the cat was cherry red. I will replace the cat and see if the problem persists.

 

[Laservision90]

Second update. After I replaced the cat, I got the same problem, frustrated I drove it home from my shop. However. After two miles of my ten mile drive, it ran like a champ, this is the second time that its dine it. Any ideas?

 

[chris00326]

Sounds like maf to me.