engine running rough

[tannerezell077]

I have a 94 chevy k1500 with the 350 tbi. I recently upgraded from the stock manifolds to long tube headers and true dual straight pipe exhaust. The day before i got the exhaust done my heater wouldn't blow hot air anymore it was just cold. Turns out it was low on coolant so I filled up the coolant and it still didn't fix the heat, i bought a new thermostat and still didn't fix the heat. My truck has a smooth idle in park but when i put it in gear it misses some and struggles to run. it runs terrible from around 1,500 rpm to about 3,000 it sputters and won't pull a hill good at all. Its terrible on gas and sucks to drive now. the spark plug wires are on correct and i even unplugged the battery for a while to see if that would reset anything but no luck. Could it be a bad o2 sensor or maybe bad engine coolant sensor?

 

[magimerlin]

Check your egr system.. is the engine light on??

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

 

[Calvinator]

I have been working on on my 95 C2500 Suburban 5.7L. I'm not a pro, but I test and learn a lot. Hope my experiences help.

Heat:
Check to see if your heater core is plugged with sediment. There are two heater hoses running to your core. With engine up to temp, those heater hoses should both be hot (150 deg in my Suburban). If one hose is hot and the other cold, your heater core is plugged. Easy fix and lots of youtube vids.

I just flushed my front and rear heater cores on my Suburban. The temp of the coolant going into the front heater core is ~150 deg. The temp of the air coming out of the front vents is ~140 degrees. The temp of the rear heater is ~120 degrees. HOT now!!

Idle:
Sensors and computer response at idle. The IAC controls air mix at idle. The O2 sensor senses exhaust mix. The MAP sensor is reading intake air pressure. The Coolant temp sensor is reading engine temp. The computer is getting inputs from these sensors and making air/fuel adjustments.

My sensors were old and I chose to replace them all with AC Delco "pro" parts. About $125 for all sensors. In my case, the IAC and O2 sensors cleared up all my idle issues. The coolant sensor was corroded and I couldn't see how it was still working!

After I replaced the sensors, I still had a stumble. I replaced my cap, rotor, wires, and plugs with AC Delco. Stumble went away. In my case, the cap had corrosion. This cap was a generic brand and it did not last 9 months.

 

[tannerezell077]

Check your egr system.. is the engine light on??

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

the check engine light comes on yes and how do i check the sysetm

 

[tannerezell077]

I have been working on on my 95 C2500 Suburban 5.7L. I'm not a pro, but I test and learn a lot. Hope my experiences help.

Heat:
Check to see if your heater core is plugged with sediment. There are two heater hoses running to your core. With engine up to temp, those heater hoses should both be hot (150 deg in my Suburban). If one hose is hot and the other cold, your heater core is plugged. Easy fix and lots of youtube vids.

I just flushed my front and rear heater cores on my Suburban. The temp of the coolant going into the front heater core is ~150 deg. The temp of the air coming out of the front vents is ~140 degrees. The temp of the rear heater is ~120 degrees. HOT now!!

Idle:
Sensors and computer response at idle. The IAC controls air mix at idle. The O2 sensor senses exhaust mix. The MAP sensor is reading intake air pressure. The Coolant temp sensor is reading engine temp. The computer is getting inputs from these sensors and making air/fuel adjustments.

My sensors were old and I chose to replace them all with AC Delco "pro" parts. About $125 for all sensors. In my case, the IAC and O2 sensors cleared up all my idle issues. The coolant sensor was corroded and I couldn't see how it was still working!

After I replaced the sensors, I still had a stumble. I replaced my cap, rotor, wires, and plugs with AC Delco. Stumble went away. In my case, the cap had corrosion. This cap was a generic brand and it did not last 9 months.

is there anything that could cause all that to happen? i know the o2 sensor could be the cause of the rough pulling and not wanting to go good in gear bc it doesn't know how much gas to add and it feels like it's getting too much gas. but i'm sure the cause of the heat because i've heart the engine temp coolant sensor could cause all of it to be out of wack

 

[tannerezell077]

update: i got a new engine coolant temp sensor and put it in to see if that would fix it. i test drove it after letting it warm up still no heat and still running rough. i unhooked the battery so maybe that would reset everything and the computer could tell there was a new part in there any other ideas on what it could be?

 

[Calvinator]

is there anything that could cause all that to happen? i know the o2 sensor could be the cause of the rough pulling and not wanting to go good in gear bc it doesn't know how much gas to add and it feels like it's getting too much gas. but i'm sure the cause of the heat because i've heart the engine temp coolant sensor could cause all of it to be out of wack

Two different subjects here..... Having no heat from the heater likely means hot engine coolant is not making it to your heater core. Coolant temp sensor doesn't control your cab heater.

The other sensors I mentioned all work together to idle your engine in/out of gear. You have to troubleshoot each one. The IAC and O2 sensors are the important ones to confirm they are working. For me, I didn't want to spend the time to troubleshoot, because I knew the sensors were older. I just bought all new AC Delco parts because they are not that expensive.

If your check engine comes on, that is a sensor problem. The computer had detected a sensor that is not operating correctly and turns on the check engine. Your truck is a 1993, so it has an OBD1 connector to check the codes. Look up how to check codes on OBD1 and then you'll figure out which sensor is acting up.


Your message also describes trouble 1500-3000 RPM. That is not idle speed. The EGR and O2 sensors system are active in that higher RPM range.

As you explore sensors, make sure you check cap and rotor too for corrosion.

And another thought, if your catalytic converter is rusted/corroded on the inside, it can restrict your exhaust, which would give you garbage performance in that 1500-3000 RPM too.

Keep troubleshooting !! Hope it is a $25 sensor

 

[tannerezell077]

Two different subjects here..... Having no heat from the heater likely means hot engine coolant is not making it to your heater core. Coolant temp sensor doesn't control your cab heater.

The other sensors I mentioned all work together to idle your engine in/out of gear. You have to troubleshoot each one. The IAC and O2 sensors are the important ones to confirm they are working. For me, I didn't want to spend the time to troubleshoot, because I knew the sensors were older. I just bought all new AC Delco parts because they are not that expensive.

If your check engine comes on, that is a sensor problem. The computer had detected a sensor that is not operating correctly and turns on the check engine. Your truck is a 1993, so it has an OBD1 connector to check the codes. Look up how to check codes on OBD1 and then you'll figure out which sensor is acting up.


Your message also describes trouble 1500-3000 RPM. That is not idle speed. The EGR and O2 sensors system are active in that higher RPM range.

As you explore sensors, make sure you check cap and rotor too for corrosion.

And another thought, if your catalytic converter is rusted/corroded on the inside, it can restrict your exhaust, which would give you garbage performance in that 1500-3000 RPM too.

Keep troubleshooting !! Hope it is a $25 sensor

thanks a bunch for the help! i think my next thing to try is the o2 sensor i've read a lot about it causing it to run rough and making the engine run rich or lean so i will try that next. i actually don't have any cats or anything on the truck just true dual straight pipes. i'm hoping the o2 sensor fixed that issue because i can live without heat.

 

[tonysomasphat102]

No heat could also be a bad heater control valve, your dashboard controls or a stuck heater door. Just a suggestion.

Sent from my Moto G (4) using Tapatalk

 

[tannerezell077]

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?