Chip & Timing
Thread Starter
Burning Brakes
Joined: Nov 2003
Posts: 1,234
Likes: 5
From: Herriman UT
Chip & Timing
I've been fighting a mild pre-detonation problem on my 86 at mid RPMS. I've had to back off base timing to 4*. I've got TPIS heads, cam, headers, ported plenum, LT runners, Stage V chip, etc. TPIS claimed the heads / gasket combo would yield 10.5 CR or therabouts. I run premium gas and the EGR system checks out OK. I've also bumped the fuel pressure which doesn't help.
I swear the pinging seems to have begun after my latest mod - the LT runners. I was able to run mid-grade gas prior.
Can something in the chip tune be causing the pinging issue?
I swear the pinging seems to have begun after my latest mod - the LT runners. I was able to run mid-grade gas prior.
Can something in the chip tune be causing the pinging issue?
Safety Car
Joined: Sep 2003
Posts: 3,599
Likes: 24
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
I'd have to see a datalog to know for sure. Do you have a way of scanning / recording data?
It is possible that the new runners are allowing just enough more air that it is now going too lean at that point, causing some detonation. What do the spark plugs look like?
If it was running correctly prior to the new runners, than I'd say the tune was ok (for the old combo). New combo might need some tuning adjustments. Did you call TPIS and ask them?
It is possible that the new runners are allowing just enough more air that it is now going too lean at that point, causing some detonation. What do the spark plugs look like?
If it was running correctly prior to the new runners, than I'd say the tune was ok (for the old combo). New combo might need some tuning adjustments. Did you call TPIS and ask them?
Thread Starter
Burning Brakes
Joined: Nov 2003
Posts: 1,234
Likes: 5
From: Herriman UT
When I bought the heads / chip from TPIS, they claimed the tune would be good when I added the LT runners later. I don't have any way of scanning. What should I be looking for with the plugs?
Safety Car
Joined: Sep 2003
Posts: 3,599
Likes: 24
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
This will tell you just about all you need to know re: spark plug reading:
http://www.4secondsflat.com/Spark_plug_reading.html
The plugs can tell you if it is running lean and/or the timing is too aggressive. It's a little more difficult than a scan, but at least it's something.
http://www.4secondsflat.com/Spark_plug_reading.html
The plugs can tell you if it is running lean and/or the timing is too aggressive. It's a little more difficult than a scan, but at least it's something.
