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Discussion Starter #1
My car is popping under acceleration. It starts at about 3500rpm and stops around 4000rpms. Is it my Vacum advance or timing or something else? I have recently installed a high flow filter and 2-3/4" intake pipe...could the increased flow cause the problems? There are no leaks in the intake (I had to heat the elbows with hot water and stretch them over the pipe) I have the AFM mod at three clicks...should I try 1 more notch?
Thanks for all help
 

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looks like you are running a little too rich... I have problems with my engine after the rebuilt due to the decreased CR from 9.2:1 to 8.0:1 on my 6M.... I am running my spare AFM with no AFM adjustments and the fuel gauge is reading 38 psi... I still have a slight popping fromt he exhaust due to too rich of a mixture... excess gas not being fully lite hits the hot exhaust and then boom... popping sound from the muffler under decelleration and every shift
 

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Discussion Starter #3
This is not under deceleration its under Acceleration. between 3500rpm and 4000rpm in third gear. It didnt do it when I had the stock intake and filter with 3 clicks but it did do it when I put on a high flow filter and intake pipe. There is no black smoke at all from the exhaust. I did another click on rthe AFM and it still does it but a little less and still no black smoke. T least if there were black smoke I would know whats going on but this... :mad:

Thanks for the input :)
 

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Mine "pops" on deceleration. Never had it do it on acceleration. Does it affect performance, or just annoying noise?
 

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Discussion Starter #5
It is accompanied by stuttering that makes the car lurch...once I am through ti the car pulls strong :?
 

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wow, i have both the problems, the lurch during acceleration and the popping sound during deceleration and when i take my foot off the accelerator, the worst of both worlds.
 

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Discussion Starter #7
Yes mine pops on deceleration too. I think the acceleration popping is a timing issue. I dont think my vacum advance is advancing very fast (82s had a vacumn advance-later models an electronic system) Or my TPS is worn at that point(3500-4000rpm)
 

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Discussion Starter #8
Well things have progressed since yesterday. I raised the back edge of the hood and removed the rubber gasket. I also put in a bottle of injector cleaner. The problem has sorted itself out. I am not sure if it was the injectors but its a good bet. I think its time for a fuel filter change.
 

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From what I have read on other car forums, Injector cleaner doesn't really do very much at all, except clog your fuel filter.

If anyone has any more expriance/knowledge o this topic it would be helpful. Maybe what I read was about a particular brand to avoid, but I find myself sceptical of "pour in" engine fixes.

My car recent has begun to sputter and hesitate at bit, but pickups at about 3800prm just fine, I also get the backfire on deceleration and every now and again onacceleration.

Carl
 

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Discussion Starter #10
I only use STP injector cleaner. It does make a difference. I notice the change almost immediately.
 

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ok lets see if i can help your sputter under exeleration is most likely a vackume problem be it a leek or advance. check all linse and conecters with the intake egr and vacume sistem. the problem lots of peeps have with injecter cleeners is the cleener will not only clean the injectors but the hole sistem. if you have lots of sediment or composits in your sistem they can become dislojed and act as a plug if the chunk is to big. or if your fillter is reddy to go all the crap in the fillter can now come out and kill your injecters.
 

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Discussion Starter #12
Yes I figure its time for a filter but I am not looking forward to the job.
I will also be putting 210s in eventually.
 

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What happens if you just lightly accelerate through the gears without going full bore WOT? Does the engine still misfire? Have you replaced any ignition system parts up to this point?
 

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Discussion Starter #14
I replaced the cap and rotor last weekend just before this started. They seem to be working OK. I didnt check the pick up but I checked the counter weights and they move freely. I dont have a vacumn pump so I cant check the distributor advance. Under light load there is no popping. Today the popping is mostly gone and the cars is running well. Good thing because I am going crusing in a couple hours :D
 

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Discussion Starter #16
I just got back from the SONIC fun run and we went about 300kms through the foothills and mountains. The air temperature was 33C(about 95 Farenhiet) and the car didnt miss a beat. Well slight popping once in a while.. I am wondering if the new ignition parts have given me a little more power and it is the clutch slipping at max torque? any thoughts on this? On a side note we lost one MK3 to BHG :roll: :) Felt bad for him I hope the auto club didnt keep him waiting to long. And the one MK4 on the run was missing a bit by the end. I had the oldest engine and it ran very strong...I was so proud of Sally :D
 
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