91 Samurai w/rich sootie exhaust

Weasel · 04-23-2009, 11:17 PM

Hi to all and hope someone hear can help me.....
I have a 1991 Samurai JL with the 1.3 TBI engine w/91000 miles on it. I purchase it with a bad miss under load. I had the ecm rebuilt and that solved that but I am having another problem. When I drive down the road, the exhaust smell gassy and there is black soot inside my tailpipe. I replaced the cap, rotor, plugs, and wires, I have very good spark in all cylinders, but still the same results. Compression was 100-110 on all cylinders. If I advance or retard the timing, I get the same results.....timing marks are on as far as I could tell. The check engine lights works and is NOT on. Hope someone can steer me in the right direction. Thanks

Weasel · 04-23-2009, 11:30 PM

Another thing I forgot to mention is that at warm idle, I can manualy open the EGR and it does not change the idle. I removed the EGR and tested it and it held vacuum. I also tested the modulator? that activates the EGR and this was good also. I did not find the holes to be plugged with carbon. My exhaust consist of headers with muffler and tailpipe...no cataletic converter.

Looz nutz · 04-24-2009, 01:25 AM

Have you ck the map sensor? This could be your problem. The ecm will read it is working fine but mechanically is not. Hope this helps.

hotrodsami · 04-24-2009, 03:37 PM

is your O2 sensor good? a bad one (or one that is not there) can make your fuel mixture to rich giving you lots of carbon. another sing that you are running to rich is if your spark plugs are black or wet looking.

jimkola · 05-02-2009, 02:35 PM

just for my info,
what brand of sparkplugs did you buy? And what brand did you remove?

Weasel · 05-02-2009, 05:53 PM

I put NGK BPR5ES plugs in and the one I took out were.....2 AC Delco R43XLS plugs and 2 Autolite Platinum AP64 plugs. I put new thermostat in and tested the water temp sensor, air temp sensor, and the BVSV sensor last night...all read consistent to what service manual said. I bought a new universal Bosch O2 sensor today but have not put it on yet.
I pinch the return line from the fuel regulator nad the engine idle dropped noticably so I figured this is functioning close to what it should. Yhanks for the replies.

jimkola · 05-02-2009, 11:24 PM

I like NGK, also Nippondenso(ND). While my work life was with Toyota, the Suzuki is very similar.
I found that AC Delco, Autolight, and Champion didn't last very long(either fouled out or sometimes the porcelain cracked). I found Bosch, and especially the "platinum" worked poorly from the very start, at least in most Asian vehicles .
One thing to keep in mind is the fuel pressure for a vehicle at idle is much lower then one under load. My Samurai is carbed, and i don't have specs for efi-but I'd imagine your fuel psi at idle is around 18-20 psi, as opposed to 30-40psi under load. While I'm not enthusastic about fuel pump being the culprit, you can't cross it off, yet. And a fuel pump going bad would not set off the check engine light.
The mass air flow sensor was a good rec. by the other reader, too. The tough part is that you have black soot, whixh would mean an awefully rich condition. Fuelpumps, mass air flow sensors, usually don't push extra gas.

Usually when an O2 sensor is bad the vehicle's ecm will default to preset values to keep the vehicle running(i.e. safe) It will usually favor a rich mix as opposed to a lean one. This would explain the soot, butt this would almost surely set off the check engine light for a rich condition. But outside of bad ignition components it's a resonable guess

Looz nutz · 05-03-2009, 07:04 PM

I have the same year sami and mine does not have an airflow sensor. Mine has a map sensor wich read air differently. On the mass air sensor the computer is reading how much air is going throuht the intake and telling the rest of the components what to do. In a map sensor the sensor is reading air pressure and adjusting air acordingly. I had a Mitsu Starion that did the same thing. I changed injectors and pump and the car ran the same. Well my friend told me to change the map sensor and that solved my problems. You dont loose anything by just inspecting the sensor. Good luck.

jimkola · 05-03-2009, 11:43 PM

Ah, thank you! That makes more sense. Appreciate the tech. info

Weasel · 08-23-2009, 11:35 PM

I am still having problems with this one.......it about kills you to drive it for the exhaust fumes are horrible. Could a weak fuel pump cause a rich charge by starving the engine of fuel and the charge not being good enough to have proper combustion? It has 30 inch tires but seems to lack power compared to my other 91.