Speedwagon Posted April 2, 2010 Share Posted April 2, 2010 At least, that's the indication it is giving me. Without time to properly get to it, I ended up running a 50/50ish mix of E85 and regular gas to get it to pass emissions. Which it did, but just barely. All indications are it runs rich. Frequent popping when I let off the accelerator, sometimes very forceful pops. And it has increased in frequency since the ambient temperature has risen. Is this a simple carb adjustment issue? Or something more? How can I tell if the car is a high altitude car, if there are no stickers under the hood(if it matters that much?)? Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 2, 2010 Share Posted April 2, 2010 It's not a carb *adjustment* issue since beyond idle speed and mixture there are no adjustment's to the stock carb - they are jetted carbs so your problem is either a clog somewhere in the primary or secondary air bleed system (which would cause a rich condition), or you are experienceing misfireing resulting in unburned fuel entering the exhaust - which in combination with exhaust leaks or even just the stock AIS system will cause backfireing - sometimes severe enough to blow holes in the muffler. It's also possible that the carb could be jetted wrong if it's been replaced. Many of these carbs were setup for feeback computer control and those units are natually jetted on the rich side and the feedback computer then controls it via metereing ports and duty solenoids. Sounds like you need to clean/rebuild the carb, fix your misfireing if you have any, fix your exhaust leaks or at least disable the AIS system with a couple quarters in the head pipes. If you don't understand any of what I just said - do some searches on "AIS*", "reed valve", and the "quarter trick". That should yeild useful posts. GD Link to comment Share on other sites More sharing options...
Speedwagon Posted April 2, 2010 Author Share Posted April 2, 2010 Are you saying that these carbs are jetted, more similar to a motorcycle carb than a standard auto carb? I do follow on what you said there though. I'll have to do some digging into those systems. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 2, 2010 Share Posted April 2, 2010 Most automotive carbs are jetted - you have to go back a long way to find stuff that is fully adjustable for mixture control. GD Link to comment Share on other sites More sharing options...
Petersubaru Posted April 2, 2010 Share Posted April 2, 2010 Not familliar with the brat..but my '86 ea82 ran very rich (the plugs were black), stumbling, and back fireing when letting off the throttle...turns out the EGR was siezed..all is working very well now Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 2, 2010 Share Posted April 2, 2010 turns out the EGR was siezed..all is working very well now Siezed closed? Many people here don't even run EGR's, including myself sometimes..... they don't affect how it runs or the mileage. If it's stuck open - big vacuum leak. That would cause a lean condition. GD Link to comment Share on other sites More sharing options...
opus Posted April 3, 2010 Share Posted April 3, 2010 Vacuum leak? Link to comment Share on other sites More sharing options...
Petersubaru Posted April 3, 2010 Share Posted April 3, 2010 Siezed closed? Many people here don't even run EGR's, including myself sometimes..... they don't affect how it runs or the mileage. If it's stuck open - big vacuum leak. That would cause a lean condition. GD ..Yes, the EGR was stuck "closed"..after reading one of your other EGR threads...I replaced that EGR with one that was working plus a new vacuum hose going to it ..my car still has the original style Hitachi carb and this simple change completely made the car run normal again..no more stuttering or miss or rich smelling exhaust smoke..the plugs stay clean now... Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 3, 2010 Share Posted April 3, 2010 Interesting - well if it works for you thats great. I've never noticed a change in how it runs with/without the EGR - there's no drawbacks to it either though so very often I will leave them in place and just make sure they are working. GD Link to comment Share on other sites More sharing options...
Qman Posted April 4, 2010 Share Posted April 4, 2010 Siezed closed? Many people here don't even run EGR's, including myself sometimes..... they don't affect how it runs or the mileage. If it's stuck open - big vacuum leak. That would cause a lean condition. GD Interesting - well if it works for you thats great. I've never noticed a change in how it runs with/without the EGR - there's no drawbacks to it either though so very often I will leave them in place and just make sure they are working. GD So, which is it... off or on... really? Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 4, 2010 Share Posted April 4, 2010 They are good for emissions, and they don't generally cause problems so I leave them in place if possible. If they aren't working or if it's a hassle to make them work I don't bother. Such as if I am using an older Weber without the port for EGR, or if I'm working on an SPFI that has a bad EGR solenoid. etc. Basically if all I have to do is hookup a hose or replace the valve itself - I'll leave them. Any work beyond that and I don't bother. GD Link to comment Share on other sites More sharing options...
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