engine running rough

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

magimerlin

I'm Awesome
Joined
May 27, 2013
Messages
2,451
Reaction score
650
Location
Raymond, NH
update: my truck is throwing codes 15 and 35 code 15 is for engine temp control sensor and i just replaced that yesterday i don't get that. code 35 is iac and i haven't tried replacing that yet but that could also be a cause of issues in having any help on the code 15?
Code 15.....
....did you replace the one on the head or the intake.... the one on the head (drivers side) is only for the temp gauge on the dash... the one on the intake is the one for the computer.....and the only one that would set a coolant temp code.. also make sure the coolant level is full and all the air is bled from the system..

Code 35 iac.....
....try cleaning the seating area first.... plenty of write ups so will not lay it out here...
....also check the tbi gasket area as that will let in unmetered air if leaking..again... lots of write ups and ways to do it...

To clear the codes on an obd1 system... disconnect the battery for about 5 minutes usually does the trick for me (when I don't have my snap-on mt2500 handy that is...lol...)

sent from what use to be a great country...
 

tannerezell077

OBS Enthusiast
Joined
Mar 26, 2016
Messages
68
Reaction score
8
Location
North carolina
Code 15.....
....did you replace the one on the head or the intake.... the one on the head (drivers side) is only for the temp gauge on the dash... the one on the intake is the one for the computer.....and the only one that would set a coolant temp code.. also make sure the coolant level is full and all the air is bled from the system..

Code 35 iac.....
....try cleaning the seating area first.... plenty of write ups so will not lay it out here...
....also check the tbi gasket area as that will let in unmetered air if leaking..again... lots of write ups and ways to do it...

To clear the codes on an obd1 system... disconnect the battery for about 5 minutes usually does the trick for me (when I don't have my snap-on mt2500 handy that is...lol...)

sent from what use to be a great country...
i replaced the one beside the thermostat and unhooked the battery after it gave the code and it's no longer giving me the code 15 it's now only saying 35. i flushed the heater core and still no heat. one of the hoses to the heater core is hot and the other one isn't. i guess tomorrow i will go out and buy the iac sensor and see if that fixes anything. i took it out today and cleaned it, it was very gross looking and worn out but i shined it up and still didn't seem to work. the heat is no longer my worry i just want the motor running like normal again i can deal without heat
 
Joined
Jan 1, 2017
Messages
36
Reaction score
6
Location
US
Do you have AC? If you do there is definitely a heater control valve. It could be run by vacuum or cable. Find the valve and see if it's hot on both sides of it. Some have a open arm that you can operate by hand, try moving or have someone inside moving the control from hot to cold and see if it's moving. Also it could be broken internally. Good luck.

Sent from my Moto G (4) using Tapatalk
 

tannerezell077

OBS Enthusiast
Joined
Mar 26, 2016
Messages
68
Reaction score
8
Location
North carolina
update: i replaced the iac and the plug wires still won't run right at all. no check engine light no codes or anything. so confused i'm thinking that my best bet is to just take it to a shop and let them deal with it
 
Joined
Jan 1, 2017
Messages
36
Reaction score
6
Location
US
I had the same problems with my 90 G20 Van. Check the two plugs and wires that go into the computer. Mine were bad and it didn't give me any codes when the oxygen sensor and almost all the other sensors were bad!!! I had to put in a new/used harness. Check the oxygen sensor and your egr. I'd start there before you give up. The ECM (computer) I think it's under the dash near the glove box.

Sent from my Moto G (4) using Tapatalk
 

tannerezell077

OBS Enthusiast
Joined
Mar 26, 2016
Messages
68
Reaction score
8
Location
North carolina
I had the same problems with my 90 G20 Van. Check the two plugs and wires that go into the computer. Mine were bad and it didn't give me any codes when the oxygen sensor and almost all the other sensors were bad!!! I had to put in a new/used harness. Check the oxygen sensor and your egr. I'd start there before you give up. The ECM (computer) I think it's under the dash near the glove box.

Sent from my Moto G (4) using Tapatalk
replaced the o2 sensor and cleaned the egr valve it seems as if the solenoid isn't creating a vacuum for the valve so could it be the solenoid causing my whole rough running problem?
 
Joined
Jan 1, 2017
Messages
36
Reaction score
6
Location
US
If you mean the egr seloniod then yes! Check all the vacuum lines again. The factory elbows on the vacuum lines tend to crack. I used all silicone vac lines no more worries. Did you clean out the egr port's under the egr? How about under the throttle body? All potential trouble spots.

Sent from my Moto G (4) using Tapatalk
 

L29Sub

I'm Awesome
Joined
Jul 31, 2013
Messages
234
Reaction score
120
Fault 35 is IAC and likely related to your idle problems (and off idle). Code 15 is indicating abnormal engine temp. The engine has two temp sensors. One for the dash guage and the other for ecm data. If the dash guage is reading 'normally" the ECT sensor, or wiring has failed. I believe that the guage sender is a single lead green wire. That has no impact on engine function. The ECT has 3 wires and has a major influence on engine operation.
The code 35 is part of the throttle body and can be induced if someone's been dinking with the throttle body or TPS.
If your dash guage indicates normal operating temp, and no heat from heater (as opposed to no fan blowing), that sucks. Very likely low coolant caused the heater core to stop up..as has been described.
Be sure that you are pulling all of the codes when scanning. The ECT (code 35) should be resolved first. Until that code is resolved, your engine remains in open loop, which nulls out O2 sensors. Runs rich. The O2 sensors set their own codes. I would not recommend replacing anything that isn't setting a code.
The heater and running problems are probably not relatedo unless you have an internal coolant leak.
Be sure that the engine control wiring is in good condition. Often as not, multiple codes are related.
Where did the missing coolant go?
Buy yourself an inexpensive OBD 1 scanner and follow the instructions. And get an inexpensive IR temp gun. Sort your heater out in 5 minutes.
Good luck!
 
Top