Help with my dune buggy 3.1 multiport V6?

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dusterdood

The Duster Guy
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I've got a dune buggy with a 3.1 V6 out of a beretta. Runs good until it warms up, and then it has a part throttle stutter. Wants to stumble and stall. I've tried spraying carb cleaner around to find the vacuum leak, and nothing. I found that when I turn the key back to the off position, I hear a shudder noise soming from the throttle body. I've traced it to this solonoid. Maybe it's the Idle solonoid that's my issue?

idle solonoid.jpg
 
dusterdood said:
I've got a dune buggy with a 3.1 V6 out of a beretta. Runs good until it warms up, and then it has a part throttle stutter. Wants to stumble and stall. I've tried spraying carb cleaner around to find the vacuum leak, and nothing. I found that when I turn the key back to the off position, I hear a shudder noise soming from the throttle body. I've traced it to this solonoid. Maybe it's the Idle solonoid that's my issue?
Click to expand...

I can't remember for the life of me which sensor that is (MAP maybe?) but anyways that sensor dose make a little noise so thats common. Without it having anything around it like firewall, hood I bet it is pretty loud.

Check your throttle sensor. Make sure that it has low voltage when it is at idle and higher voltage as you move the throttle bodies arm. (Motor off, key in run position)
 
That thing is your idle control valve. If the idle speed seems fine that is not it. Check the air intake temperature sensor and the coolant temperature sensors. Both will decrease in resistance as temperature increases. Not sure of values for your engine.
 
that is a idle air control valve they just control idle speed what year 3.1 do you have does it have a mass air flow sensor it will be big and in the air boot to the throttle body they are common to cause that kind of problem expecialy if it got dropped or banged around they are fragile. if they get dirty. early years did not have them though.
 
Could be the pcv valve also. The signal they recieve changes with engine temp.
 
I'm sorry guys, I don't get E-mail notification here, and forgot where I posted this. I pulled th IAC apart, and cleaned the carbon off, and it worked for the noise it was making. I think it was trying to 'park', and couldn't find the correct position. It does have MAF, and I don't know what year it is. I checked the oxygen sensor voltage, which I was told should be around 450 milivolts. I got weird readings, and replaced it ($20), and it's a bit better. Still seems sputtery at part throttle, but only after it reaches operating temp. When you fitst start it it's in some pre programed mode, where the sensor readings don't seem to matter.
The PCV would be connected into the air inlet tube right after the MAF sensor? There's this 90 degree plastic fitting that's not connected to anything. And a black plastic tube coming off the valve cover. Maybe I need it reconnected? Would there be a conventional PCV inline?
Mike
 
It accepts gas at full throttle, and still runs strong, so I don't think so. It's just at part throttle.
 
Do you have any pic's. Just want to check out your buggy. I try to make it out to the Glamis sand dunns in the winter. It is a lot of fun.
 
Very nice. Looks like a little light weight car. I bet it has a good power to weight ratio with that V-6. You could try going over to Glamisdunnes.com I think it is. Thay have a post board and a lot of expereance with buggys. My Dad is a member over there.

Good luck hope you get it running right.
 
It weighs 1100 and had 140 Horse with the cats. I did a burn out in my drive way and it runs strong, but I live up here in the snow belt, so it's got to go (don't care for the yellow CHEBBY across the back either). I'd love to trade it for an A body (hint, hint), but there's a guy locally who's interested, and has a freaky AMC spirit with sidepipes. I'm thinking of trading him. Need to figure out this part throttle stumble. Hmmm...
Mike
 
The black plastic line is your PCV line. If there are more than 50000 miles on this engine chances are your problem is caused by the throttle position sensor. It is mounted on the end of the throttle shaft, opposite the throttle cable. They spend most of their lives in one little area of the potentiometer and the carbon wears off, causing screwy resistance readings just off idle. Don't forget to disconnect the battery and reset the computer after you change a sensor. Hope this helps.
 
if it does have a maf sensor. i work at a chevy garage. unhook the sensor and run it that way. if the sensor is failed. the car should show improvement with it unhooked.
 
I checked the TPS, and the voltage seems right. I also checked the coolant temp sensor, and it's OK. I got weird readings from the MAP sensor. The 5 Volts referance was fine, but it's sensor reading is higher at idle and drops to about 2.3 volts at WOT. I think that's backward, and it's bad, anyone know for sure?
 
is this 90 % fitting coming out of the t body boot,or,intake manifold.........any vacuum leak will cause a prob in closed loop......thought you said you sprayed carb cleaner around.?.............need more info on the 90 that is not connected..good luck
 
The 90 degree fitting is coming out of the air boot, just downstream of the MAF sensor. I rigged up an old style PCV valve out of one of my valve covers, so it wouldn't suck air. Should I just plug it up?
 
I'm a dummy, the sensor that I thought was the MAP is the throttle position sensor. I guess I lost track of what I'd tested already. The engine runs better with the MAF disconnected. There's no MAP that I can find. The only MAF sensors listed online are all for 2.8 V6s, and I don't want to buy the wrong one. Can I just leave the MAF disconnected? What if I buy the (non-returnable) 2.8 MAF one? I still don't know how to tell what year this is, but they only have MAF sensors listed for '87-'89, and the 3.1 started in '90.
AAAArghhhhh!
 
the cavaliers and then malibus had 3.1 engines from early 90-91 up until around 2001. call a gm dealer tomorrow and have them do a check for you on the years they all fit. good chance they were all the same those years. if so let me know. i can buy you 1 for 10% over cost. usually they have a 67% markup over cost. shipping would be pretty cheap. or you can and should be able to get one from a local parts store. but we have had alot of trouble with the parts store electronic stuff. Like I said in my other post. I definatley would have unhooked it and tried it. I am glad you used my advice. Makes a guy feel helpful once in awhile. don't get alot of that anymore. You could probably be ok to run it unhooked but the vehicle may burn alittle more fuel or not enough..
 
your not going to have both maf ,map if, it run better with the maf dis connected its most likley the maf ............that the way we use to check them back then..........if its a hot wire...should be ...you could try cleaning it with a q tip and rubbing al...your prob running a k@n air cleaner being that its a sand buggy... there are known for getting the oil and dirt in to the maf.... also if you dont know were that 90% out of the boot goes plug it for now...... good luck
 
I did plug the 90 degree opening with a PVC from a muscle car era one. Still got the Pentastar on it!
I'll clean the connections, and see if it'll help. Otherwise, I'll have to buy one, and they only have one listed for the 2.8.
No ill effects from leaving it unplugged?
 
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