Now I understand...( acceleration issue)

daves87rs

daves87rs

Joined
Feb 23, 2009
Messages
19,460
Location
Michigan
Now I understand why the Cobalt gets the rep it does. While dependable- I’ve never seen a GM with so many odd issues....and I’ve owned a few! Sorry about the rant, so here is the story...

I’ve been chasing issues with this car since I have owned it. This one has me stumped.. So before I replace half the car in anger... The car in question is a 2006 Cobalt with the 2.2 Ecotec . And it has two current issues: Lack of acceleration (in stop and go traffic) and running rough. Here’s what throws me: It seems to happen when it is warmer/humid. We have had two cooler days in a row, and the car runs and idles better. Just drove it around this morning for 15 minutes, and it was like nothing had been going on for the last few weeks.... The one thing I have noticed is that the problem is getting worse, but again only when it is warmer....

Not sure where to start: Could be fuel related (fuel pump, fuel sending unit) engine (coils. Plugs are newer) even the timing. (Though the chain makes no noise) Looking for ideas I could try... The car seems to be fine once it is up to speed (and passes fine) but struggles coming from a stop) Car also has 110k....

Looking to my friends for ideas!
 
I’ve noticed the same thing on a similar type vehicle and confirmed by another long time member on here. However last year or two haven’t noticed it but have done a bunch of preventative maintenance and replacing a leaking intake manifold gasket which is a common issue on the 05 Toyota 1zz 1.8 engine.
 
I had an 06 Vue with same problems and only fix was going to 89 octane gas. The 2.2 is a good engine if run on interstate you will get over 200k but if driven mainly in city it will carbon up causing the problems. I pulled plug with 30k on them and all 4 had carbon deposit. Took it down interstate and held to the floor up to 80 with black smoke from all the carbon. I drove it up to 140k with problem starting around 90k ran exclusively 89 cause 87 it would stall on accelerating from a stop. I did eventually get 02 heater code which I replaced that only helped idle smooth out. 2 oxygen sensors in 50k. Cleaned throttle body once a year, plugs at 30k. Nothing ever showed up as a problem on tech 2 that I borrowed from dealership or Snap on. Carbon was soaking up gas. I did seafoam but that was a short fix for a city car.
 
Do you wash your engine bay? Check the coils/boots and add dielectric grease if they are dry. On warmer/humid days you could be getting some boot tracking/shorting. Also check engine ground straps for tight/clean connections. Washing under hood can cause electrical issues unnecessarily. Cleaning the MAF is a cheap check also and have you looked at the plugs for good tan color?
 
Kawiguy454 said:
Do you wash your engine bay? Check the coils/boots and add dielectric grease if they are dry. On warmer/humid days you could be getting some boot tracking/shorting. Also check engine ground straps for tight/clean connections. Washing under hood can cause electrical issues unnecessarily. Cleaning the MAF is a cheap check also and have you looked at the plugs for good tan color?
Click to expand...

Nope, I do clean it by hand though......Afraid I might break something....
 
This car is too much! :-O

With some cooler days, the car goes back to norMal. But, it had a bad running day yesterday. But better running today.

Think it might not hurt to replace the Knock sensor first to see it if helps.....
 
clinebarger said:
Being a Chevrolet....It likely has both MAP & MAF sensors.
Click to expand...
Good to know! So, on the MAF Ford's of the era I'm familiar, BP was measured with a MAP exposed to atmosphere whilst the MAF was used to measure air volume (EEC-IV MAF cars and SD to MAF conversions). Is this setup the same way or is BP inferred from the MAF and MAP is used as a MAP?
 
I am thinking it is one of the sensors, as it seems to be jekell and Hyde some days.

Two things I have also noticed while working with the car : Gas mileage has dropped. There is also a little oil on the pass side of the engine block, by the belts/Starter/ throttle body.......
 
OVERKILL said:
Good to know! So, on the MAF Ford's of the era I'm familiar, BP was measured with a MAP exposed to atmosphere whilst the MAF was used to measure air volume (EEC-IV MAF cars and SD to MAF conversions). Is this setup the same way or is BP inferred from the MAF and MAP is used as a MAP?
Click to expand...

BP is read by the MAP (Before the engine is started) & Air mass/Load is calculated from the MAF inputs. The MAP inputs are used for sanity checks as well as "Back-up" is case of MAF failure.
 
daves87rs said:
I am thinking it is one of the sensors, as it seems to be jekell and Hyde some days.

Two things I have also noticed while working with the car : Gas mileage has dropped. There is also a little oil on the pass side of the engine block, by the belts/Starter/ throttle body.......
Click to expand...

I would start with cleaning the MAF sensor.
 
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