running like crap

[duanep]

A few weeks ago my 1.3 L fuel injected (75,000 km) Samurai started running very poorly. Rough on idle after about a minute and an almost impossible to drive hesitation during any kind of acceleration.

It has new wires, plugs, cap, PVC valve and new fuel filter but that did nothing. I was short on time/experience to do any real trouble shooting and I wanted it running so I took it to my local mechanic. He spent 1.5 hours on it and couldn't track down the problem. Said it was not a fuel delivery problem, and said he could not get the computer to output any codes. He checked the TPS and started looking for a bad ground but he said it could take him a while and wasn't sure how much I wanted to spend on it. He still thinks it is a bad ground. I took it home and started checking ground wires, removing and cleaning any I could find. Next I disconnected the O2 sensor while it was running to see if it had any effect, and didn't. It also didn't bring in the check engine light either. Last summer the wire fell off and the check engine light came in.

Anyone have any suggestions? I know there is a lot of threads about the computers on the early 90s models failing but from what I read most of the time the engine fails to run totally. Do you think this could be a ground problem, or computer problem?

Thanks in advance…d

[fullspectrum]

Is this happening only after the idle comes down after cold start? So it runs well until warm? I had a dodge daytona that had a bad MAP sensor or MAS air flow sensor I forget..but on cold start it was ok until warm then it ran like a bag of crap. What was happening was the computer used the O2 sensor to sense the fuel mixture on cold start and then it switched over to the MAP sensor which was bad and it ran like crap. So I shoulda just bought a MAP sensor but temporarily I just pulled the temp sending unit out to fool the computer to thinking the engine was always cold. I had to wire up a manual switch for the fan but it worked for awhile. The car cost me $100. Point is maybe you can check to see if this is the problem by pulling the temp sending unit off. I'm not sure if the Sammy puter adjusts mixture the same way or if it even has a MAP sensor...it just sounded similar to the problem I had.

[Buggy]

i agree with fullspectrum check you mass air flow sensor try unpluging it and see if it smooths out is it running rich? black smoke out the tail pipe when you step on the gas? this would tell alot. could be something simple like a ground if your going to trace wires save some time get at least a chilton book some thing with wire schematics in the back.make sure your check engine light works too.

[Evolvocane]

Is this happening only after the idle comes down after cold start? So it runs well until warm? I had a dodge daytona that had a bad MAP sensor or MAS air flow sensor I forget..but on cold start it was ok until warm then it ran like a bag of crap. What was happening was the computer used the O2 sensor to sense the fuel mixture on cold start and then it switched over to the MAP sensor which was bad and it ran like crap. So I shoulda just bought a MAP sensor but temporarily I just pulled the temp sending unit out to fool the computer to thinking the engine was always cold. I had to wire up a manual switch for the fan but it worked for awhile. The car cost me $100. Point is maybe you can check to see if this is the problem by pulling the temp sending unit off. I'm not sure if the Sammy puter adjusts mixture the same way or if it even has a MAP sensor...it just sounded similar to the problem I had.


OBD1 and OBD2 systems dont use the o2 untill the computer goes into closed loop. I.e. when its warm.

[Zuklin]

Any chance of water in the tank?? My LWB started acting up after i knocked off the fuel filler cap. It rained into the tank and started running like shat before i noticed the cap was gone.

[Fullload]

Your sammy doesn't have a MASS air flow sensor. It woul dbe the mAP but that would really not make it run that bad.

Go under the dash and switch your relays around. Your fuel pump relay with your main relay. i'm thinking that's the problem. It only takes a second to see but it's located under your glovebox and they are attached to the ecm.
Check to make sure that your dizzy ground is in good order as well. ( been burned by that one before too)

[fullspectrum]

OBD1 and OBD2 systems dont use the o2 untill the computer goes into closed loop. I.e. when its warm.

My Dodge Daytona was an 89..I would guess that is OBD1? This was about 6 years ago but I found some info saying that the mixture was regulated by the computer with a set mixture (getting a signal that the engine was cold from the temp sending unit) on cold start and then switched over to the O2 sensor for mixture feedback once warm (closed loop). Sorry I had my figures mixed up..it was a long time ago. And I don't believe it was the map sensor it was the O2 sensor. So to test it I fooled the computer into thinking the engine was cold all the time. I pulled the plug off the temp sending unit and plugged it into one a had from spare parts. Sure enough as long as the engine thought it was cold it ran well. Because the engine thought it was cold the electric fan would never come on though.

[Buggy]

genral rule 96 and up are OBD 2

[duanep]

thanks for all the input!! I have tried cleaning all the grounds and it hasn't helped. I was able to force in the check engine light so it is working. I don't think I have any water in the gas tank Dave but to tell you the truth it is near impossible to drive the way it is, so I haven't been able to put a tank threw it. I have added some stuff to the tank to for that though. I couldn't find a MAF sensor so I am glad to here there isn't one there. I will swap over the relays on the ECM and see what happens. I presume the fuel pump one is working, but what does the other one do? Will it likely not run at all if that one is working? WHat does an O2 sensor sensor cost, does anyone know?

thanks again for all the help,

[Jester-]

Not sure for a sammy, but for my kick(mind you it was a heated direct fit) cost me like $130.00.

You might be able to get a universal for like 30 bucks though.

[Fullload]

thanks for all the input!! I have tried cleaning all the grounds and it hasn't helped. I was able to force in the check engine light so it is working. I don't think I have any water in the gas tank Dave but to tell you the truth it is near impossible to drive the way it is, so I haven't been able to put a tank threw it. I have added some stuff to the tank to for that though. I couldn't find a MAF sensor so I am glad to here there isn't one there. I will swap over the relays on the ECM and see what happens. I presume the fuel pump one is working, but what does the other one do? Will it likely not run at all if that one is working? WHat does an O2 sensor sensor cost, does anyone know?

thanks again for all the help,


Technically your right. the other relay is your main power relay. If that becomes old and intermittent it may not be sending 12 volts through the system all of the time, and messing with your sensors.
So after you switch them around turn the key ahead ( but not to start) and put a hand on the relay and feel for the click. Do it a couple of times to see if it works and then feel it when it is running.
check all of your plugs etc... and wiggle them while it it running. It took me 40 hours of pissing with a DIS sundbird to find out two wires were getting a bad contact at the plug in connector to the Coil packs. It threw me every engine code in the book. So now i do not rule out anything.

[zuki709]

o2 sensor should only be $20 or $30 i think the one jester put in his kick is probably the 4 wire o2 sensor? the sammys are single wire sensor. and the where come in a lot of vehicles. but i never had any problem with my old swift running bad when the o2 sensor went i drove it for 4 or 5 month befor i changed it.

[fullspectrum]

WHat does an O2 sensor sensor cost, does anyone know?

thanks again for all the help, Before you buy one, check to see if it runs ok with the O2 sensor disabled. Pull the temp sending unit wire off and start it up cold. Not sure but you may need to have that wire grounded to the engine.
This way it will keep running off the fuel mixture preset for cold start by the computer. If it runs ok and stays running ok than I would assume it's the O2 sensor. This is how it worked on my Daytona anyways...it's worth a try. Does anyone know if his Sammy has one or two temp sending units? One for the guages and one to send info to the computer?

[duanep]

Well I checked all of the grounds on the ECM and they seemed to be fine. I checked the grounds to the firewall, and from the block as well. I swapped the relays on the ECM as well and everything seemed fine. wiggled every wire I could find. next I tested the inputs to the ECM. When I got to the MAP sensor, because it is such a pain to test, I just unplugged it and took it out for a spin. It drove way better, very slight hesitation, but not the severe lack of power with it plugged in. Could I just need a new MAP sensor? Any idea were I could get one, or does someone have a functioning used one they want to get rid of?

on another note, my O2 sensor is a single wire unit and I called the dealer to see what a new one was worth.....$200?!?!? what are they crazy? Were can I get one of these $20 ones.

thanks again for all the help. Also if anyone is interested the Haynes manual is a way better manual than the chilton. It has all of the wiring diagrams, and ECM codes and pin connnector numbers for the ECMs, etc, etc that the chilton does not have

d.