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Hey folks,
Looking for sage advice on getting my 88 GW to pass Smog testing. Engine is freshly rebuilt. New Edelbrock Intake and 1400 Carb. Edelbrock Cam and bored .30 over. Vacuum lines all new and verified 20 times over! Idle screws are 3/4 out. RPM is 650 in gear.
Just tried today and am at 62 and need to under 25 for CO.
Looking at the graph it is pegging way up there! Runs great but have not been able to drive in 2 years as I worked through the rebuild and now smog.
I am going to pull the top off the carb to check jet/needle size.
At the end of my limit and may throw in the towel.
Any ideas?
Thanks
Brad
PS: I have a pair of front seats out of an old explorer, anyone want 'em? My butt is too wide!
I wonder if adding some zddp additive to an oil change would help. Sounds more like a timing issue vs a wear issue though. There are some sharp guys on here that can probably help with better info.
thank you for posting the plot/result, this is what everyone with smog issues should do, because all the gases are related.
When you fail because your CO or carbon monoxide is too high, that means the fuel and air ratio is way off and there is incomplete combustion of the air/fuel mixture. Some common causes are spark plugs, spark plug wires, misadjusted timing or vacuum leaks.
You fixed the vacuum leaks, no mentions of spark plug wires of other timing values, but start with the stuff that cost time not $,
I would check for misfire and specialy lean misfire, not familiar with the Edelbrock baseline adjustments, but on most carbs from ford to japanese bike, the idle screw base is 1.5 turns from slightly seated.
In Cal we do ppm, not gram per mile, and we get a number for 15 and 25mph, not a continous plot from 0 to 55mph. What is very suspicious are the spikes during the testing, like the tester has pedal to the metal for a few seconds (X axis looks to be time), which surely will dump raw gas and make the combustion incomplete, the speed measured is slower after the spike, seems like somebody is making sure that you are failling.
It would be nice if other Co people could post the plot of their results
Other questions, what are the failing limits for the other gases?
Michel
74 wag (349 Kmiles... parked, next step is a rust free body)
85 Gwag (229 Kmiles... the running test lab)
This makes sense to me....previous time I went a gent there was able to get it to pass, but during visual they saw the hose that delivers air to Cat had rotted some so failed on visual. I changed the hose in the parking lot and had to retest. New driver and had readults similar to what you see. Maybe I am running so lean that the driver felt he needed to spike it to meet the drive line they follow....
As for sparkplugs new with the rebuild, same for plug wires. At this altitude I had to jet down some, it was way rich.
Thanks for replying. More to think about for sure.
Buy the Spring Kit, you will need it and is cheap. Pull the metering rods out (this takes 5 min) and look at the stamping on the side, should have 4 numbers (7547) should be stock for the 1406, not a bad place to start. What altitude are you? I am running a 6847 on mine, pretty stock setup. I was able to get mine to run pretty good at low to mid rpm's with both the 7347 and the 7047. I was up about 5.5k ft last weekend and had no issue, that is about as high as I can get around here.
The first two numbers are your low throttle meter rod thickness, the lower the number the more fuel you will get, the 2nd two numbers are your power mode, 47 is good for me, but you might need to go with a larger number if at altitude.
which altitude are you at? and recheck timing to match your sticker which is around 17 degrees for high altitude
Good luck
Michel
74 wag (349 Kmiles... parked, next step is a rust free body)
85 Gwag (229 Kmiles... the running test lab)
I too had similar issues with my 89. After 3 failed tests and rebuilt carb and complete tune up I found my ignition coil was about 3/10ths of an ohm out of spec on the primary side. Doesn't sound like much until you multiply that by about 200 to get the spark on the secondary side. Not enough for complete burn especially on deceleration as indicated on the graph. New coil and numbers dropped to half of limit levels. Do a quick resistance check on the coil to rule it out. Can't remember exact specs but a quick look in Chilton guide or online should tell you what to look for
'89 Grand Wagoneer, bought it for $500 bone stock 207k miles, 4" BDS all spring lift, ZJ fuel tank conversion behind axle. Work in progress. ••$$$