'85 GLH, stock, 120K miles, no codes (haven't compression or leak-down tested yet). It runs like a top except: Under mild acceleration I hear pinging - if I go WOT, the pinging goes away. Is this a fuel issue (filter or pump - neither have been replaced, yet - I know, stupid for a car that's been sitting for 10 years), or a sensor issue? I always run premium gas.
Verify that your timing is to specification- marks aligned properly at TDC, and when you check with a timing light. Then go from there. Keep us posted
G.P.
I can say that it's set just right - I replaced the timing belt (was forced by a broken one), set it incorrectly (one tooth off) on the side of the road, and then redid, re-checked, re-aligned (timing marks, dist. slot, and flywheel), and buttoned up at home. It runs awesome except for this issue. IGN timing is set for 10*. I'll have to look, I don't recall if I'm running RN9YC or RN12YC plugs.
Another note, it seems to happen more when the car is well into operating temp. I warm up the car before going anywhere - within 10 miles of my commute (40 miles one way) it will start doing this. If the car is still a bit cool, I don't hear it
Not good.
You may not be able to hear at WOT what you can hear at partial throttle.
I had the same situation - just a matter of time and I cracked a stock cast piston. To be safer, turn your timing back to 8*
Yes, change the filter ASAP; cheap. Then confirm fuel pressure and then flow - time it into a graduated container. Could be an injector too.
Could be result of changes in the blend of gas that is available to you. Are they adding alcohol to gas in WA? If so, the affect is a leaner mixture. They are here in CA and it does make a difference - winter gas runs differently than summer gas.
John Laing
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It could also be a fautly EGR valve, and that can cause you to ping under cruise especially on the T1 log motors... Is there any codes? When i had my T1 log car, and removed the EGR setup from my motor it pinged like crazy when at cruising speed just like whats happening to your car... Try backing the timing off to 8* and see it the pinging goes away... thats the base timing i had to run to get rid of the pinging on my car. Maybe it's just the noisy slider cam your hearing?
Yes... check the status of your EGR system. I removed mine from my stock '86 and didn't have any problems, but I have heard other people say that it produced detonation. At WOT the computer runs rich. At part throttle the computer adjusts mixture based on readings produced by the O2 sensor, and runs leaner than at WOT. Part throttle ping is a common problem, especially on cars that use manual boost control. You may have excessive carbon built up in the engine also.
Thanks guys!! - I dialed the IGN timing back to ~8* and the ping went away (or was FAR less "hearable"). I did notice when I changed the plugs originally that it looked like there was quite a bit of carbon buildup on the pistons (peering thru the plug holes). The ping had me worried since I never had this issue on the SL at any throttle. This should give me time to go thru some of the other stuff I need to do and still drive it (until I get the SL to pass e-check). Next on the list - fuel filter.
Are you using premium fuel?
Always (See post#1)!!Originally Posted by Dusty_Duster
I was having a similar issue. I found some of the suggestions here difficult to believe for my issue because it seemed to happen over night. I'd just had some work done on the a/c. I looked under the hood and the sensor with only 1 wire going to it on top of the log manifold was disconnected. I don't know what it does, but after reconnecting that, it all runs fine, the part throttle ping went away, and I can burn 87. BTW - '86 Turbo Z Daytona.
Sounds like your knock sensor or air temp sensor (not too familiar with the log cars) was unplugged. That would do it.
That is a great candidate for detonation right there. It's possible you may not "hear" pinging but still you may be knocking. Other factors may aid to why you're not hearing knock... exhaust noise, road noise, wind noise, etc. Get a scanner and read the knock voltage. Read the coolant temperature voltage as well. I forget the values for which, but I believe for coolant temp. around 160-190*F it should be about 3-3.5V. Both are very important. Maybe someone can give help us out with how much voltage the knock sensor should be sending once detected.
What scanner would y'all recommend? Also, short of a tear-down or installing water injection, is there a good way to clean the carbon buildup off? I may just shotgun replace the sensors since the car was sitting so long prior to my purchase, but curiosity has me wondering what their voltage values are currently.
Seafoam seems to work okay for removing heavy carbon deposits.
Ran some Seafoam through, replaced knock sensor (and a couple guage senders), replaced the fuel filter. So far (still at 8* base IGN timing - I did find I could still catch rapid knock at that setting occasionally prior to these changes) it runs smoother and better than ever, and no sign of knock (yet?). More sensors are going on the replacement plan as soon as they arrive.
Should I try bumping up IGN timing back to stock yet?
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