skully Posted November 7, 2008 Share Posted November 7, 2008 My L28 Turbo is coughing on me on boost - I've checked the basics - it really only happens when I am trying to spin up the boost / accelerate - I can slowly gain speed and boost, but it coughs when punching it. It Seems like a AFM issue, but all test show as OK on TPS and AFM - any suggestoins on what to check or troubleshoot? Throttle response in park is fine, revs nicely - no issues there- just under driving conditions... Quote Link to comment Share on other sites More sharing options...
skully Posted November 9, 2008 Author Share Posted November 9, 2008 Bump-Anyone have any ideas on this one? Quote Link to comment Share on other sites More sharing options...
Clifton Posted November 9, 2008 Share Posted November 9, 2008 If you can build boost slowly but can't punch it. It sounds like TPS/ accel. Is this stand alone? Did you check it with a analog meter or DVM? Quote Link to comment Share on other sites More sharing options...
skully Posted November 11, 2008 Author Share Posted November 11, 2008 stock 81 - I used a Analog Meter to check the TPS switch when I R&R it' a few years ago Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted November 11, 2008 Share Posted November 11, 2008 unplug the o2 sensor and see if it still does it. Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted November 12, 2008 Share Posted November 12, 2008 How much boost are you running? What did you set your spark plug gap to? I had to reduce my gap to .028 when I was running 12 psi of boost. HB280ZT Quote Link to comment Share on other sites More sharing options...
skully Posted November 12, 2008 Author Share Posted November 12, 2008 stock boost - stock gap on the plugs - I did just replaced the plugs thinking I had a firing issue -checked the wires, same thing as before all Fule injectors seem to be working - I can hear them opening / pulsating - O2 is tricky - stock O2 sensor - can't get the damn thing out - even with days of oil penetration lube (no jokes please... with 02 tool -- it does still run the same at idle, but I haven't unplugged the o2 and driven it around...Would the cough sound be more like a wastegate issue? The turbo is fairly old but seems to spin up under no load just fine, only when the car is under load that it's doing this.... Quote Link to comment Share on other sites More sharing options...
Armand Posted November 12, 2008 Share Posted November 12, 2008 When it "coughs" does it make any abnormal sounds? If there is any high pitched whistling or even pinging you should check out all the gaskets from header to turbo or and turbo to downpipe. The turbo on my sr20 was doing the same thing a couple days ago and I tracked it down to that. It sounds like your problem is probably different if it isn't those making sounds. Quote Link to comment Share on other sites More sharing options...
skully Posted November 13, 2008 Author Share Posted November 13, 2008 it's more like a backfire thru the turbo that when I apply throttle, that it boggs down and coughs, if I ease off,and it's ok - how touchy are the 81 pickups on the Crank angle sensor - thinking it's more of a timing issue Quote Link to comment Share on other sites More sharing options...
Clifton Posted November 13, 2008 Share Posted November 13, 2008 it's more like a backfire thru the turbo that when I apply throttle, that it boggs down and coughs, if I ease off,and it's ok - how touchy are the 81 pickups on the Crank angle sensor - thinking it's more of a timing issue If it's backfiring through the intake/turbo and ONLY under load, it's too lean. If it's all the time it could be a valve timing issue but then you wouldn't be able to drive it. Quote Link to comment Share on other sites More sharing options...
skully Posted November 14, 2008 Author Share Posted November 14, 2008 Good Point. I'll check the FI pressure, regulator and TPS this weekend. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted November 17, 2008 Share Posted November 17, 2008 Remove the cover over the ecu by the driver's left foot and wiggle the connectors on the ecu while driving. You might need someone else to watch as it's hard to see and wiggle them at the same tiem. Quote Link to comment Share on other sites More sharing options...
loy Posted November 20, 2008 Share Posted November 20, 2008 So any update on your situation? Quote Link to comment Share on other sites More sharing options...
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