84 Hot Air GN backfires at 1700 rpm

Gbodyslim

New Member
Joined
Nov 14, 2020
Car backfires when cruising in 2nd gear at 1700 rpm and when I'm park at 1700 rpm. Was rich and rough at idle but changed maf and o2 sensor and now she idles fine. All numbers on scanmaster are in range except blm was 102, tps was .57 at idle, and volts was 12. Got a 200 amp alternator. Haven't installed because I have a slight coolant leak from water pump so I want to replace that while alt is out. I have a TA33 turbo, 42 lb injectors. 86/87 ecm, ls1 maf, translated, extender chip, adjustable wastegate, fuel pressure regulator, and 340 fuel pump. Looking to be pointed in right direction! Thanks!
 

conn84gn

Well-Known Member
Joined
Jul 13, 2005
Could be lot's of possible problems
I would start with a compression check on all cylinders and seen what you have
 

TireFryer

Now I know how clouds are made...
Joined
Dec 21, 2001
Car backfires when cruising in 2nd gear at 1700 rpm and when I'm park at 1700 rpm. Was rich and rough at idle but changed maf and o2 sensor and now she idles fine. All numbers on scanmaster are in range except blm was 102, tps was .57 at idle, and volts was 12. Got a 200 amp alternator. Haven't installed because I have a slight coolant leak from water pump so I want to replace that while alt is out. I have a TA33 turbo, 42 lb injectors. 86/87 ecm, ls1 maf, translated, extender chip, adjustable wastegate, fuel pressure regulator, and 340 fuel pump. Looking to be pointed in right direction! Thanks!
Set your tps properly. It’s way to high. Also you need to figure out why your chip is pulling so much fuel. Start with setting iac and tps.
 

cool 84

Got hotair?
Joined
May 27, 2001
Is it backfiring through the intake or exhaust? If it’s not obvious, does the boost gauge spike a little when it backfires? It’s pulling a ton of fuel, to compensate for a (supposed) rich condition. 02 sensor good? So it runs ok below and above 1,700rpm? The only time I had an issue like this was when the cam sensor was so far off it would jump in to next or previous window and give a horrendous backfire and it also seemed like the fueling was never right. Do you by chance have a dead misfire causing it to pull all that fuel since the 02 is seeing raw fuel from a dead cylinder?
 

Gbodyslim

New Member
Joined
Nov 14, 2020
Set your tps properly. It’s way to high. Also you need to figure out why your chip is pulling so much fuel. Start with setting iac and tps.
Thx for the reply. How do you set TPS and IAC? I read that you cant set IAC. I cant see where there is a screw on my throttle body. I believe the 84 throttle body may be different, but I cant see where to adjust it.
 

Gbodyslim

New Member
Joined
Nov 14, 2020
Is it backfiring through the intake or exhaust? If it’s not obvious, does the boost gauge spike a little when it backfires? It’s pulling a ton of fuel, to compensate for a (supposed) rich condition. 02 sensor good? So it runs ok below and above 1,700rpm? The only time I had an issue like this was when the cam sensor was so far off it would jump in to next or previous window and give a horrendous backfire and it also seemed like the fueling was never right. Do you by chance have a dead misfire causing it to pull all that fuel since the 02 is seeing raw fuel from a dead cylinder?
Thx for reply. O2 sensor is new. MAF is new. Gauge doesn't spike, but it runs fine below 1700 once it backfires I get out of it. When I'm driving it sounds like its coming from bottom of car, but when I rev engine in park it comes out exhaust. It ran fine before all upgrades, so I'm not sure if its cam sensor. It starts fine and idles fine now since I changed O2. Was very rich at start but not so much since I changed O2. Also there are no codes on Scanmaster. I am going to change out ccci to 86/87 since I am running 86/87 ecm. I dint think I have a dead cylinder. Wouldn't it run sporadic? Let me know your thoughts! Thx
 

TireFryer

Now I know how clouds are made...
Joined
Dec 21, 2001

'87 Turbo "T"

What a complete shitshow!!
Joined
Jul 28, 2020

Read all this. Super helpful and lots and lots of information. ^^^^^^

Here's the troubleshooting page for the hot air cars.


Also, there's this little channel on youtube, called TurboBuicks101... I'm not quite sure who he is... but he knows his stuff and has vids on almost every sensor and how to's and how to reset sensors and most anything about our cars. https://www.youtube.com/channel/UCx5FoeyV2MovRUIlqWOdBag/videos
I believe he(TurboBuicks101) is Scooby Doo on here. Somebody correct me if I’m wrong.

Good channel with good info.
 

Gbodyslim

New Member
Joined
Nov 14, 2020

Read all this. Super helpful and lots and lots of information. ^^^^^^

Here's the troubleshooting page for the hot air cars.


Also, there's this little channel on youtube, called TurboBuicks101... I'm not quite sure who he is... but he knows his stuff and has vids on almost every sensor and how to's and how to reset sensors and most anything about our cars. https://www.youtube.com/channel/UCx5FoeyV2MovRUIlqWOdBag/videos
Thx buddy. I follow turbobuick101. That's where I got info for ccci upgrade. Thanks for the info. I will post results of what I figure out!
 
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