2G Rough idle, low rpm, and seems to run rich

[Rosey2G]

Hey guys, first off, I thought about posting this in engine tuning, but I figured since I'm not only new to DSM's, but also mechanics, that the Noob forum would be best, since that's exactly what I am. I have also spent a few hours trying to sift through search results, so far with no luck.

Currently, there are still unknowns about exactly what kind of condition the car is in mechanically, but I do have some observations and questions in regards to them. The car will start, but it runs very rough, and will not rev past 2.5k rpm even when floored. It sounds as though it's running rich.

There is a known fuel leak from the rail where the injector sits in cylinder 1. I purchased a set of cheap 850's off ebay, got them cleaned and flow checked, and the guy said they seemed to flow at about 850cc, when compared to 1000's and 500's.

My original plan was to just replace stock injectors with the 850's, and then use the MAFT to adjust accordingly. However, a friend of mine said it's possible to flood the engine and hydrolock it by putting the new injectors in and not having a tune for it.

I currently have 3 different MAF sensors, two spares and the one on the vehicle. There are no brands or logos on the two spares, but the serial number sticker on the bottom is two different styles, which leads me to believe they would be different manufacturers. Is there a way for me to figure out which is which, or if they're the same? Can I also safely drop in the 850's, mess with the fuel settings in the MAFT and have the car run well? Or should I try to get an injector o ring set to try and solve the leak first that way and fix the running rough?

This does also mean I don't currently know if I have a GM sensor or if it's still stock.

I have worked for parts stores, so I'm familiar with parts and usually how they go together. But as for the working mechanics and the various skills and knowledge past basic maintenance, is still very unknown to me. So I'm trying to learn as much as I can before I do something wrong, thinking it's alright, and then end up costing myself even more money.

If there are articles or other resources that I can't find or don't know about, please let me know where I can find them so I can search through them as well.

 

[steve]

Your profile for this car is a little sparse here.

Running 850cc injectors with any tuning device that is based on lying to the ECU about airflow (like the MAFT or SAFC) causes the ECU to think the engine load is very low and you wind up with big timing advances. The rule of thumb is 650cc max on these tuning systems.

Which "stock" injectors are currently in there and what is your MAFT set to?
For now I'm suggesting you get a fresh set of injector insulators, sheets, and o-rings for what's in there currently assuming they are stockish.

Have you got a current idea of compression, and checked for any vacuum leaks?

What do the spark plugs look like? Are they fresh?

Since you have a 95, do you know if it has an EPROM ECU?

 

[Rosey2G]

Profile is sparse, as what I know for certain on this car is very sparse. From what I've been told by the previous owner, a 7 bolt was swapped in not long ago. I have the paper work showing this, however, it doesn't say whether or not it's actually a 7 bolt. It also doesn't specify how many miles are on it or whether or not it was rebuilt. MAFT is also not currently hooked up, so I should still be running stock tune, 450's, unknown MAF.

Plugs have not been pulled yet, nor has compression been checked. I think I can borrow a compression Guage from my friend though. As for leaks, I think I had one before, and my friend pulled off the hose from the BOV back into the intake because it was NOT the right size at all and very cracked and damaged. He told me I can run my BOV to atmosphere, because he did it all the time (Honda, Toyota guy). We've since gotten into numerous arguments cuz I tell him I can't run BOV to atm in my current stock condition, but he insists I can. He does not seem to believe it will cause issues like every one here has said.

As for ECU, I do not know yet. I saw an article about how to check if it's an EPROM, but I haven't had the opportunity yet to go rooting around and confirm yet.

I will definitely pull injectors, try to verify size and get some new seals. I know previous owner did a coil pack conversion, so no more wires. But I'll also swap out plugs and see if im able to get the fuel leakage sorted out.

Thanks for letting me know about the 650's being max, that wasn't in any info I could find.

 

[Rosey2G]

Alrighty, I've got an update. I've been able to get some time to work on it a bit. Started pulling apart the fuel rail and valve cover. Found cylinder 4 to have oil to the top of the spark plug. Pulled plugs, swapped for BPR6EKN's. Replaced valve cover gasket and valve stem seals, did a compression test. Cylinders 1 and 2 are about 120-125. Cylinder 3 is about 135, and cylinder 4 that had the oil, measured at about 145-150. I have not yet been able to check for vacuum leaks, but my BOV is currently to atmosphere until I get a correctly fitted hose to recirculate.

The fuel injector for cylinder 1 is still leaking from the rail, between the injector and rail. I replaced both the thick black spacer at the bottom, and the o ring around the top of the injector. The leak is also decently large, so once I get more time I'm going to take the rail off the car and see if I can figure out why it's leaking. I do also have an EPROM ECU.