Major bogging/no throttle response/hesitation, mostly at cold starts
12-12-2017, 03:02 PM
#1
Major bogging/no throttle response/hesitation, mostly at cold starts I've done some major searching and can't seem to find the exact solution..
Saab 9-7x 5.3, 222/224 113 cam, heads, LSA supercharger, LS7 MAF, stock TB, Flex Fuel... The car has been fully dyno tuned.
So here's the issue, on a cold start, typically in the morning, the engine start right up. I'll let it warm up for a minute or two, once I put it in drive, it looks like it runs lean (19-20s on AF gauge) and there is no throttle response. I'll keep giving it gas and won't go, but it's still idling. Then it will start bogging/hesitating like rough idle, and won't move. Then like 5-10 seconds later it takes off, then goes back to no throttle. After about 5-10 mins warming up, it drives well. Except sometimes, it will comes back and if I am crusing on the freeway, and give it light gas, it does the same thing. WOT is great after the car warms up..
At this point, I'm thinking its the MAF sensor, or the throttle body sensor... Any ideas?
Saab 9-7x 5.3, 222/224 113 cam, heads, LSA supercharger, LS7 MAF, stock TB, Flex Fuel... The car has been fully dyno tuned.
So here's the issue, on a cold start, typically in the morning, the engine start right up. I'll let it warm up for a minute or two, once I put it in drive, it looks like it runs lean (19-20s on AF gauge) and there is no throttle response. I'll keep giving it gas and won't go, but it's still idling. Then it will start bogging/hesitating like rough idle, and won't move. Then like 5-10 seconds later it takes off, then goes back to no throttle. After about 5-10 mins warming up, it drives well. Except sometimes, it will comes back and if I am crusing on the freeway, and give it light gas, it does the same thing. WOT is great after the car warms up..
At this point, I'm thinking its the MAF sensor, or the throttle body sensor... Any ideas?
12-12-2017, 08:59 PM
#3
Dyno tunes usually focus on wot fueling. Probably why it does fine at wot. Sounds to me like your open loop fueling needs some serious work. Most likely only reason it drives fine once warm, is bc fuel trims are bringing it back inline via stock o2s.
i would get it street tuned for sure.
i would get it street tuned for sure.
12-13-2017, 05:59 AM
#4
9 Second Club
I've done some major searching and can't seem to find the exact solution..
Saab 9-7x 5.3, 222/224 113 cam, heads, LSA supercharger, LS7 MAF, stock TB, Flex Fuel... The car has been fully dyno tuned.
So here's the issue, on a cold start, typically in the morning, the engine start right up. I'll let it warm up for a minute or two, once I put it in drive, it looks like it runs lean (19-20s on AF gauge) and there is no throttle response. I'll keep giving it gas and won't go, but it's still idling. Then it will start bogging/hesitating like rough idle, and won't move. Then like 5-10 seconds later it takes off, then goes back to no throttle. After about 5-10 mins warming up, it drives well. Except sometimes, it will comes back and if I am crusing on the freeway, and give it light gas, it does the same thing. WOT is great after the car warms up..
At this point, I'm thinking its the MAF sensor, or the throttle body sensor... Any ideas?
Saab 9-7x 5.3, 222/224 113 cam, heads, LSA supercharger, LS7 MAF, stock TB, Flex Fuel... The car has been fully dyno tuned.
So here's the issue, on a cold start, typically in the morning, the engine start right up. I'll let it warm up for a minute or two, once I put it in drive, it looks like it runs lean (19-20s on AF gauge) and there is no throttle response. I'll keep giving it gas and won't go, but it's still idling. Then it will start bogging/hesitating like rough idle, and won't move. Then like 5-10 seconds later it takes off, then goes back to no throttle. After about 5-10 mins warming up, it drives well. Except sometimes, it will comes back and if I am crusing on the freeway, and give it light gas, it does the same thing. WOT is great after the car warms up..
At this point, I'm thinking its the MAF sensor, or the throttle body sensor... Any ideas?
And are you implying the car was fine before and this is a new problem, or a problem that has always existed ?
12-13-2017, 07:43 AM
#5
Dyno tunes usually focus on wot fueling. Probably why it does fine at wot. Sounds to me like your open loop fueling needs some serious work. Most likely only reason it drives fine once warm, is bc fuel trims are bringing it back inline via stock o2s.
i would get it street tuned for sure.
i would get it street tuned for sure.
Super tuners.
12-13-2017, 10:17 AM
#6
Dyno tunes usually focus on wot fueling. Probably why it does fine at wot. Sounds to me like your open loop fueling needs some serious work. Most likely only reason it drives fine once warm, is bc fuel trims are bringing it back inline via stock o2s.
i would get it street tuned for sure.
i would get it street tuned for sure.
12-13-2017, 10:20 AM
#7
A new problem after a few weeks of my first tune it starting happening, now it happens where its become every cold start up and intermediately. That's why I'm guessing its my TPS. After my last tune, there was a lot of other fuel and trans issues fixed, but this one still remains.
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12-13-2017, 10:52 AM
#8
A new problem after a few weeks of my first tune it starting happening, now it happens where its become every cold start up and intermediately. That's why I'm guessing its my TPS. After my last tune, there was a lot of other fuel and trans issues fixed, but this one still remains.
12-13-2017, 05:02 PM
#9
A new problem after a few weeks of my first tune it starting happening, now it happens where its become every cold start up and intermediately. That's why I'm guessing its my TPS. After my last tune, there was a lot of other fuel and trans issues fixed, but this one still remains.
My Procharged 1998 Z28 exhibited same symptoms. Over time a rubber connector on a vacuum line deteriorated and finally cracked while simply moving some lines checking to make sure there were no leaks. After 10 years or so this stuff deteriorates and breaks down.
Of course that was after buying a new tps and idle air control valve both of which I didn't need (about a $100).
.
12-13-2017, 05:04 PM
#10
12-14-2017, 12:55 PM
#11
I'm going to check the throttle body, maf sensor, and vacuum lines, rule those out. Then back to the tuner and have him work on that open loop fueling... But come to think of it, I don't have any vac lines in the intake to the crank case.
12-14-2017, 09:41 PM
#14
Sorry - my mistake - brain dead I guess
I was reading this post.
https://ls1tech.com/forums/generatio...or-option.html
I was reading this post.
https://ls1tech.com/forums/generatio...or-option.html
12-15-2017, 03:24 PM
#16
9 Second Club
Really it should be easy....GM has done most of the work for you, so you're just working with their base.
But it still doesnt seem quite clear as to whether this is a new problem, ie it ran correctly before, but now it does not, with no changes having been made beforehand...and as such a fault. Or if it has never run correctly...ie never been tuned correctly for all the mods in place.
Obviously depending on which, you need to go two different directions to resolve
But it still doesnt seem quite clear as to whether this is a new problem, ie it ran correctly before, but now it does not, with no changes having been made beforehand...and as such a fault. Or if it has never run correctly...ie never been tuned correctly for all the mods in place.
Obviously depending on which, you need to go two different directions to resolve
12-21-2017, 03:12 PM
#19
SO I swapped the MAF sensor and throttle body and sensors, checked all the wire connections, still have the same issue. There are no codes, so it can't be the 02 Sensor... So next up, back to the tuner. I'll find out fuel tables and check out the open look fueling with him.