93 3.4 v6 that i was told that it keeps switching between closed and open loos,,what will cause this?? car runs good and then starts to sputter and when i accelerate into higher rpms check engine light comes on and it seems to run good,,then after a few minutes later light goes out and it will sputter again,,i;ve changed map sensor coil packs,ignition module,tps,new plugs and wires,,local parts house don't have a scanner to read codes so it looks like im shooting in the dark,,what should be next?

 

Get a scanner, all we can do is guess.

 

<rant>You know, nobody should have to get their car scanned, this feature should be BUILT IN to ALL CARS! </rant>

;-)

 

Could be a bad temperature sensor (not the temp sending unit for your gauge). When the engine gets to a certain temp, the sensor tells the computer to switch from open loop to closed loop. It's still a stab in the dark though, but I see you haven't replaced that part yet!

 

It used to be

Most of the time when I get a car that wont stay in closed loop you need to install new O2 sensor(s). New O2 sensors fix about 30% of the cars. The other 70% had something wrong that caused the O2 sensors to foul out. There are a lot of codes that will not set while the car is in open loop so its a catch 22. You want to fix anything you can find before you replace the O2 sensors but you may find new issues once you install the new O2 sensor.

 

My Chrysler 300M daily driver has that feature built in. Trouble codes are displayed in place of the odometer numbers. If broke **** Crysler can do it, there is no reason why better heeled car makers can't. lol

 

steveh3500,if you changed all these parts chasing this problem,you could have bought a cheap scanner/code reader and maybe saved some money.without having it scanned we are all just chasing it as well.could be and egr valve,which you could check and clean for free or perhaps iac(idle air control)valve..also cheap check and clean,bad relay in fuse box under hood or a multitude of issues.see what i'm getting at?

 

your right about that for sure ,,i keep throwing in the dark replacing all these parts but i just bought this car and got it cheaper than i was expecting ,,so while throwing at it it does have alot of nice new parts on it,,but now after replacing coolant sensor and still the same,,time to just break down and buy a scanner,,but i'm afraid to get the wrong one after i keep hearing how this particular year has to have a scanner and not just a reader,,does anyone know of one that will work for sure on this year 93,,will a autoxray e-z scan 3000,,work ?

 

i have the actron cp9150 kit(not top of line but works great).is a cp9145 but i guess the cables for gm obd-1,obd-2,chrsyler and ford cables make it the 9150 kit.i use it on my 95 Z-28(obd-1 with obd-2 plug).can monitor sensors,fuel,o-2's etc. as well as read and erase codes.can leave it hooked up to monitor systems but should have someone else in car as it is a lil hard to monitor and drive.i monitor all my data about once a month and compare it to previous readings.nice when you have those occasional "ghosh ses lights"come on then go off.can also use it on multiple different cars.

 

oops,meant ghost lights.lol