Nisif

Car: 91 Civic Dx Hatch, converted to obd1 and mpfi
Setup: Stock block B18a1 with arp head studs, Garrett t3/t4 50 trim, street tuned on crome

Be prepared for a story, no cliff notes lol... I appreciate your patience

I've ran this setup with relatively no issues for 35,000 miles. Problems occurred after filling up with 93 at a Valero station. Gas tank was nearly empty before fill up. Left station and nearly a 1/4 mile later car began to stutter horribly throughout rpm range. Turned around drove 1/4 mile back to my house and parked the car. I drained the tank the following night and put in "good" Shell 93 fuel. No luck...the same symptoms were still apparent and the car was hardly driveable due to the misfire and stutter.

This occurred almost a year ago. Unfortunately the car hasn't been a priority due to multiple reasons until now... I Really miss driving it.

I've swapped out numerous parts with "known good" parts to no avail. Then re-installed the original parts after finding out it didn't fix the issue. Although it would seem apparent it's a case of bad fuel I even swapped out ignition/electronic components as well just in case. Here is a list of the work I've completed since the problem:

-Swapped out and tried a new motorola map sensor
-Checked ecu map sensor pinouts for proper voltage and voltage at map sensor 1/21/11
-Swapped out the distributor
-Swapped out the resistor box
-Swapped out ecus (both are OBD1 and socketed for eprom chips)
-Swapped out Eprom chip with a backup chip with the same basemap
-Changed spark plug wires

-Swapped out fuel injectors with another good set of DSM 450s
-Installed new fuel filter
-Used Fuel Injector Cleaner

-Replaced engine with another "known good" running b18a1 with consistent compression numbers across all 4 cylinders. I did this more so because my problematic Civic was sitting collecting dust, and I needed the original engine for a build up in another car.

-Removed Walbro Fuel Pump and forced compressed air throughout the hard fuel lines from the tank to firewall to clean out fuel lines.

After all this I STILL have the same problem. Here are the accurate symptoms even after taking the walbro fuel pump out of the tank and installing it in auxiliary tank that fed into a a short fuel hose with banjo fittings directly to the fuel rail:

SYMPTOMS:
-No Check Engine Lights
-Initially one of the spark plugs was fouled. I had an issue with Cylinder #3 misfiring but that was corrected after installing new spark plugs. I tested voltage to all 4 injectors and they are receiving voltage.
-After installing 4 new spark plugs the car runs on all 4 cylinders (I confirmed by pulling injector plugs and spark plug wires and noticed an obvious difference after doing so)
-Engine ran better when hot on the new spark plugs.
-After letting the engine cool and especially on colder starts the engine will stutter badly around 1,000 rpms or lower around idle when giving it throttle.

Afterwards I put the walbro fuel pump back in the car's fuel tank and tried again. Same problems as above but slightly worse. The engine will backfire, stutter, and misfire.

At this point I need suggestions. Can a fuel pump be "defective" or clogged even though I'm getting fuel pressure as indicated by the gauge on top of the fuel filter (see video)? >>>Installed a new walbro fuel pump, it didn't correct the problem (posted below) Should I install a wideband 02 sensor to see what the AF ratios are (I'm willing to buy one if I can determine the problem)?

Here is a video of it running (I'm verballing calling out directions before engaging throttle, etc) About 1:50 minutes into the video it shows fuel pressure readings while engaging throttle:

http://www.youtube.com/watch?v=pTOzkIQk17I

habib

Sounds like a une problem, do you have your tuned saved on your laptop. Try to reupload the tune on to your ecu

dcmatt

iTrader: (7)

Fuel pumps can go bad. Having a wideband would def help you determine if its a fuel issue.

joe2844

Of all the things you mentioned you never said if you replaced fuel filter...It may have got clogged and you will still have pressure but no volume...

Turbo-LS

iTrader: (4)

sounds like clogged fuel filter or a just abotu dead fuel pump

Nisif

I have a second eprom chip with the same basemap that I already swapped out. I listed that above. It still ran the same.

I may end up purchasing one, unless I find someone I can borrow it from. I know I'm getting some fuel as indicated by the fuel pressure gauge but I'm not sure if it's enough fuel.

I listed that above in the original post. The fuel filter has been replaced, actually I believe I replaced it twice, before and after cleaning the fuel lines out.

Well I know its not a "Dead" fuel pump because it turns on and provides fuel or else it wouldn't run at all. The last time I pulled the fuel pump out, the filter bag/screen on the fuel pump didn't look extremely clogged but maybe it's causing an issue??

I'm really wondering if anyone else has had similar symptoms and has received Enough fuel pressure to run the car, albeit horribly, but the fuel pump was indeed the problem. It'd be reassuring to know before I drop around $100 on a new fuel pump.

Turbo-LS

iTrader: (4)

fuel pressure and fuel volume are two different things you could be getting pressure but not enough volume. essentially a clogged will act as a smaller flowing pump it will give you pressure but the amoutn of fuel it moves in a given time period will be dramatically less. thats the differences between a stock pump and a walbro pump.

Nisif

That makes sense...excellent point. I ordered a new Walbro 255lph pump tonight. I'll post results after it's installed. Fingers are crossed...

Nisif

Update:

So I finally received the new 255 lph walbro fuel pump (GSS341) to replace the walbro GSS341 I had before. I installed it hoping my problem would be resolved and the problem was a contaminated or faulty fuel pump. The car still runs horribly as it did before. I'm getting 35 psi of fuel pressure at idle like I did before when it ran correctly. I really have no idea what to diagnose or try replacing next.

I ordered a B&M adjustable fpr kit that should arrive tomorrow. I will try to play around with the fuel pressure settings to see if it helps. I'm currently running a stock fpr and have been which worked well when it ran right.

Feel free to contribute any ideas...

kyden

those b&m units are garbage. find another oem fpr.

Nisif

I've already tried another oem fpr with no success. The B&M will be temporarily installed to see if the car runs any better after adjusting fuel pressure.

Nisif

Another update:

I installed a B&M adjustable fuel pressure regulator and adjusted the fuel pressure settings to see if it would correctly the problem. No success, again car runs better when the engine is warm but it still continues to bog and misfire when the engine is cold.

I'm running out of ideas...

javierb14

Do you have any way of recording/logging ecu data? If somethings out of whack, the data should show it.

Nisif

I personally do not have a wideband o2 sensor and much tuning experience. Although at this point I'm more than willing to purchase one and learn the basics aspects of tuning or recording afr and related data. Gives me an excuse to learn something new, and hopefully sort out this issue...

I ran the car again today, with the engine cold AND running disconnecting fuel (pulling injector harness) or spark (pulling plug wire) to cylinder 2 did not impact the already current crappy running condition of the engine. Although when the engine warms up it's apparent that the pulling fuel and/or spark to cylinder 2 makes an impact on its performance.

Btw, on a sidenote, i followed your signature link. Based upon the pictures i saw, you're one hell of an artist...very nice welds and fab. Can you pm with starting prices on the "BEVO" turbo manifold?

DDTECH

comp and leakdown test time.

Turbo-LS

iTrader: (4)

Agreed, cold motor it has issues hot motor its better, sounds like things are sealing up when it gets hot making it run better

Nisif

I've had the same results with a known good engine and this motor that I swapped in after the problem occured. Although for piece of mind, I'll do another compression and leakdown test. Should have time to do so within the next 2 days. I'll keep you posted...Thanks for keeping up with the thread

1997civicdx

Try swap injectors from one cyl to another- see if the problem follows the injector or stays with the cyl.

Nisif

I just purchased and installed a set of "refurbished" DSM 450cc injectors. All four have been cleaned and bench flowed.

After installing the new injectors the engine still does not run correctly. I'm going to contact my tuner and see if i can get a wideband installed to get readings. I already know it's running rich at idle after looking at the plugs. I'm hoping it just needs retuned after installing new injectors and a new fuel pump (even though they're the same size and flow rates).