ok so this 91 DX hatch... it was running funny/rich etc with the original motor (even after replacing fuel filter, plugs, dist cap and rotor, injectors, and igniter).

After 15 mins or so of running the cat would start glowing red hot.

Anyways, I have swapped in a D16A6 and finished the MPFI conversion as well, and put a brand new catalytic converter on.

Started her up 2 days ago and still after about 15 mins the cat started glowing red hot again...

All things considered, we're guessing maybe the fuel return line is somehow clogged or kinked - making fuel pressure in the rail way too high causing this super rich condition (exhaust smells like raw unburnt gas even once warmed up).

If this is the case how are you supposed to un-clog it? Is there anything else that could be causing it to run so ultra rich? The other thing I noticed aside from the red hot cat and exhaust that smells of unburnt fuel was that when you blip the throttle it pops out the intake.

What else would be causing a super-rich condition like this even with literally everything in the engine bay new? (didn't change the plug wires because they tested fine to spec).

Any help will be very appreciated

 

I take it your not recieving any codes?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike9571 &raquo;</TD></TR><TR><TD CLASS="quote">I take it your not recieving any codes?</TD></TR></TABLE>
correct. Not throwing any codes at all, just running crazy way too rich. This is just confusing the poop out of me because the only thing that was reused was the plug wires with all tested perfectly fine (resistance in spec, and I tested each one with a spark plug in the end and they all sparked fine too).

 

Have you tried substituting the ECU?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike9571 &raquo;</TD></TR><TR><TD CLASS="quote">Have you tried substituting the ECU?</TD></TR></TABLE>
well yeah sorta... I mean the car was a DPFI so it came with a PM5 ecu. Since we converted the car to MPFI with the D16A6 motor swap we're also using the MPFI ecu out of the EX.

It's just strange that with 2 completely different engines/intake and fuel systems/ECU's that the car is still running unnaturally rich

 

Ha yea i thought about that after i asked. You didnt mention checking the fuel filter, did you? It does seem like there is a fault somewhere in the lines. If thats the case they sell cleaner that you poor in with gas. I dont think its very affective though

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike9571 &raquo;</TD></TR><TR><TD CLASS="quote">Ha yea i thought about that after i asked. You didnt mention checking the fuel filter, did you? It does seem like there is a fault somewhere in the lines. If thats the case they sell cleaner that you poor in with gas. I dont think its very affective though</TD></TR></TABLE>
The fuel filter is new, and we replaced the line that runs from the firewall to filter because the original one snapped while taking the banjo bolt out. The line from filter to fuel rail is still the original one.

That was what led me to guess that maybe the return line is clogged. All I can tell right now is that it's getting an excessive amount of gas, what with the popping on throttle-blip and glowing red hot catalytic converter heh

 

bump

Anybody have any input on this problem?

Also, it seems the gas cap is not sealing very well... wouldn't that cause a lower-than-spec pressure rather than too high of one?

 

bump

 

You can always try a different fuel rail and injectors, Try using a CRx PM6 ECU just to see what happens.

Have you checked your timing at all? When you say you're checking for codes are you waiting to see if the CEL light comes on the cluster or are you checking for a blinking light on the ECU?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wickedEFguy &raquo;</TD></TR><TR><TD CLASS="quote">You can always try a different fuel rail and injectors, Try using a CRx PM6 ECU just to see what happens.

Have you checked your timing at all? When you say you're checking for codes are you waiting to see if the CEL light comes on the cluster or are you checking for a blinking light on the ECU?</TD></TR></TABLE>
Timing is dead on (timing belt as well as ignition); The CEL doesn't come on aside from when you first put the key in, but I was referring to the ECU - it doesn't flash any codes.

it just seems kind of fishy that two completely differen engines and fuel/ignition systems would both be running insanely rich in the same car if it's not something else on the car isn't the prob ya know?

Is there any way a fuel pump can go bad that would cause increased pressure, or a bad gas cap maybe?

 

both me and you are having the same problems dude. my car is runnign rich . Im getting about 19mpg. my gas cap isnt sealing all the way either. this all happened after my fuel pump swap!

BUMP FOR HELP

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kalm_traveler &raquo;</TD></TR><TR><TD CLASS="quote">After 15 mins or so of running the cat would start glowing red hot.</TD></TR></TABLE>

Usually means the cat is bad/clogged. I've seen it happen about three times in my life and caused severe power loss or performance when it happened. Change it or disconnect it from the header and see if that helps. Hope this helps and good luck... ...Manny.

edit: reading owns me.


Modified by EF9Si-T at 8:43 PM 12/28/2007

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EF9Si-T &raquo;</TD></TR><TR><TD CLASS="quote">

Usually means the cat is bad/clogged. I've seen it happen about three times in my life and caused severe power loss or performance when it happened. Change it or disconnect it from the header and see if that helps. Hope this helps and good luck... ...Manny.

edit: reading owns me.


Modified by EF9Si-T at 8:43 PM 12/28/2007</TD></TR></TABLE>
it has a brand new cat now - replaced it when I did the motor swap

 

disconnect the car or the mid pipe and see if the mpg are the same which i doubt would change weird problem try asking your local mechanics shop.
They might be able to figure it out let em see it.

 

have you checked your fuel pressure with a guage?

 

no and if the pressure is to high wat getting a fuel pressure reglator

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jpciii &raquo;</TD></TR><TR><TD CLASS="quote">have you checked your fuel pressure with a guage?</TD></TR></TABLE>
Not yet - I'm going to 'borrow' one from Autozone now to check it - that's just a semi-educated guess given everything that has been swapped/replaced.

Since the car was stock D15B2 w/ dual-point injection and we've replaced it with a D16A6 w/ MPFI, as well as new plugs, new catalyst, new fuel filter, new igniter, etc.

I'll post up when I know for sure what the fuel pressure is sitting at.

 

nvm Autozone says they don't have any FP testers.

Anyways, the only things remaining from the old D15B2 DPFI stuff in/around the engine bay are as follows:

spark plug wires (these test fine with resistance, and they spark visibly)
MAP sensor
possibly the o2 sensor (not sure which exhaust manifold I bolted on to the A6)

<U>The following are new/different</U>:
catalyst
distributor
igniter
ECU
fuel injection system
fuel filter
dist cap & rotor
PCV valve
--

Still not throwing any codes. It starts up basically like normal, idles relatively smooth but after about 15-20 mins of running the catalyst still glows red hot and everything near it on the underside of the car starts smoking from heat.

This is exactly what happened with the old D15B2 and DPFI, which is why I did the motor/FI swap in the first place.

Seriously, if anybody can come up with whatever idea solves the problem I'll buy them lunch

 

OMFG.... I have got to be the worlds biggest idiot

Ok so I picked up that car for $400 knowing that it needed a t-belt. I had a new one laying around so slapped it on - car ran just as it has been even with this new motor and MPFI.

After replacing part after part trying to figure it out, I ended up doing the motor swap, then eventually MPFI swap. Nothing seemed to make any difference.


Tonight, my buddy who used to work at Honda comes and checks everything I had checked. It's all groovy like I thought. Then, he looks at the wires on the distributor cap.

1-3-2-4? he says. Um..dude, it's 1-3-4-2, you have 2 and 4 backwards. We switch them, car starts immediately, idles silky smooth, doesn't pop when you blip the throttle, warms up faster, and best of all <U>NO MORE GLOWING CATALYST</U>!!!!

HAPPY NEW YEARS H-T!!