Stumbles over 3500Rpm and 1/4 throttle

[fuforums]

Well, I checked the map sensor because I got codes 14, 15, and 21. It tests fine. I got 5 volts, good ground, and from .650 v to over 2volts when I tapped the throttle. So I guess its good. Its pretty clean and the wires all look ok. The vacuum lines are good as well. The 4 way connector had one that popped out but I put it back. Still no change.

I unplugged both plugs at the throttle body and the top one made it idle very low almost shutting off but it stayed running. The bottom plug out had no effects.

When I push the throttle I get normal power up to about 1/4 throttle. At that point it just bogs down and then quickly tries to rev but bogs back down and it does this till I get back to under quarter throttle. Its just up and down up and down. Like when the throttle body opens up more than and eighth of an inch it just bogs. Kinds like on an old choke vehicle or weed wacker when you try to squeeze the gas all the way and if its still cold it will bog and make a deep throaty sound like its getting too much fuel. But it does this even after the engine has reached temperature and the fan is on.

What could it be? Seems if it were fuel filter it wouldn't be at exact the same throttle position each time and it wouldn't get to 3500 rpm and feel and sound so powerful. If I smash the pedal to the floor it still does it and its instantly. Its not like it tuckers out and can't go higher, something is making it cut out.

Any help is welcome. Thanks for the replies so far.

Joe
1991 Dodge Shadow Turbo ES 2.5 Intercooled
Savannah, Ga.

[WVRampage]

Mine did that once and it was the plug in for teh injectors was dirty i cleaned it good and put some dieletric grease on it and its fine now.

[fuforums]

Well, I DID unplug the injector plug to get to the fuel hoses BUT not before I cranked it the first time and the symptoms showed up then before I messed with the plug. I'll check the plug again, though just to make sure. I did see that the ground straps were all in place and there's no rust or anything like that so all grounds are good as far as I can tell. Thanks for the reply.

[R/T]

Sounds like the throttle position sensor - TPS.

[1quik4]

Change distributor pick-up. This happened to me as well.

[fuforums]

I'll check the dist. pickup. Could be some corrosion in there. Can you test the TPS or should I just buy a new one? 35 bucks might as well try it I guess. Seems like limp mode but the MAP sensor checks out ok, I can't figure it out.

[fuforums]

Ok, so I get a new TPS and put it on, I unplug and check all plugs making sure they are clean, I pull the dist. cap and check it and clean the contacts, I check all vac. hoses etc. Then, I notice at the driver's side firewall there is the main harness and some wires are visible. I pull it out some and see that two wires are chewed (by squirrels which were living under the hood) and one of them was just scraped but the other was in half totally. It was GREEN with RED stripe.... the MAP sensor wire. I checked it with the meter and verified that that was it and so I soldered it back together and there it was. NO CODES. It's a great feeling when it cranks right up, idle settles down nice and low, purrs good, and everything is right.

I took it down the side street 4 times to see how it would run. Ran great, pulled hard boosted up but then on the last run I noticed that it only gave me 5psi of boost. I don't have a tag on it yet so I went down the street real quick and still only 5psi. It has a grainger valve, I addded an intercooler to it being a 2.5 so I know it's something simple but I can't remember what causes it to go back to minimum 5psi. Wastegate vac line? I looked quickly but didnt' see anything disconnected but it was getting dark and I was tired so I parked it. So, what to check now? Otherwise it runs great. IT's on LOW FUEL too so I know it's almost outta gas and I didnt' wanna run out with an expried tag so I'll get the tag tomorrow and then fill up and then wash it and all that but I want my boost. I forgot how freaking fast this car is. FUN to drive too.

thanks for all the help.



Joe
1991 Dodge Shadow ES Turbo Intercooled
Savannah, GA

[fuforums]

Did a little checking and one of the screws holding my BOV to the intake tube came off allowing the boost to squeeze out past 5psi. SO, I put a new screw in there, and got her started up. Ran good but was stumbling. I added some gas and it powered right up!

Went to the gas station filled up, took it to the car wash, looks way better now. My wipers broke, though. I'll post another thread to see about that.

joe

[GLHSKEN]

Congrats on waking the car up. The windshield wiper issue is not that common, but it does occur.