ratdude747 Posted July 1, 2022 Share Posted July 1, 2022 Last week I bought myself an early birthday present in the form of some upgraded TFI iginition parts for my 1984 4.9. Parts list: Used parts bought off of Nickelplate on the classified forum: -McCully Racing Remote TFI Kit, With a 3rd party TFI module and (made by somebody else) dummy TFI module and breakout cable. -MSD 8227 TFI Blaster Coil New from RockAuto: -United Motor Products 28624 Premium Tuneup Kit (Cap, rotor, wires, and accessories) In addition to these being intended to be an upgrade, I was having an issue where I was getting random misfires under load and every time I'd stomp the gas, the engine would faceplant. I confirmed that my accelerator pump was spitting fuel so I ruled that out for the latter. I performed and completed the install last night. Here's some pics: Remote TFI installation: I decided to install it under the cruise control servo: Yes, it does clear the bracket: Dummy TFI module installed: After that I swapped the cap, rotor, and wires. The wires had been swapped recently and the coil/rotor a bit less so, but I couldn't remember where I used "good" parts and where I used "get me on the road" parts. Not to mention this brand's premium caps and rotors are blue, which IMHO looks good on my engine! After all of that, it ran but still had the "faceplant" issue (wasn't able to test drive anywhere to test the other issue). So, the next move was to swap my cheap parts store coil for the MSD. I hadn't swapped it initially because after buying it I found a lot of reviews stating they were trouble. But, I figured it was worth a shot... and per some test driving today, voila, no more faceplant! Final pics of the setup: One note- see that old looking cap screw? That's because I destroyed the new one. A PO had ruined the threads there by using a sheet metal screw; I thought I had already fixed it (forgetting to check the screws on the old cap... nope. Thankfully I had an M6 tap floating around so I was able to retap it and use the one "correct" screw on the old cap. Gotta love previous PO's... http://www.garysgaragemahal.com/uploads/6/5/8/7/65879365/florida-man-42_orig.jpg All in all, I'm happy. I'll do some proper testing this weekend (as part of my travels related to my birthday) to confirm all is back to normal/better. Link to comment Share on other sites More sharing options...
Gary Lewis Posted July 1, 2022 Share Posted July 1, 2022 Excellent! Not only looks better but runs better. So the faceplant problem was apparently the coil. But the reviews say the MSD coil can be a problem. Do they say if the coil went bad for them or if the coil took the TFI module out? I'm just wondering about having a spare under the seat, but don't know which thing to have a spare for. EDIT: Happy Birthday! Hope you have a fun trip. Link to comment Share on other sites More sharing options...
ratdude747 Posted July 1, 2022 Author Share Posted July 1, 2022 Excellent! Not only looks better but runs better. So the faceplant problem was apparently the coil. But the reviews say the MSD coil can be a problem. Do they say if the coil went bad for them or if the coil took the TFI module out? I'm just wondering about having a spare under the seat, but don't know which thing to have a spare for. EDIT: Happy Birthday! Hope you have a fun trip. No mentions of TFI failure. The gist I've gotten is that MSD's QC went down the can when they moved production to China... this coil is old enough that it may be made in USA. Or perhaps old enough to be past the "infant mortality" age. I didn't recall seeing "China" stamped on it anywhere, so it is possible. I do have my old TFI module... an AZ one that I've had nearly as long as I've had the truck (going on three years later this month). Link to comment Share on other sites More sharing options...
Gary Lewis Posted July 1, 2022 Share Posted July 1, 2022 No mentions of TFI failure. The gist I've gotten is that MSD's QC went down the can when they moved production to China... this coil is old enough that it may be made in USA. Or perhaps old enough to be past the "infant mortality" age. I didn't recall seeing "China" stamped on it anywhere, so it is possible. I do have my old TFI module... an AZ one that I've had nearly as long as I've had the truck (going on three years later this month). In my experience coils are binary - they work or they don't. But in your case it appears the spark was arcing inside the coil when the cylinder pressure came up enough to make jumping in the coil easier than jumping across the plug's gap. In that case you could back off the throttle and keep driving. But if the MSD fails I'll bet it FAILS. So it might be wise to have a spare. However, coils are pretty common so you should be able to get one at any parts store - if you can get to one. Link to comment Share on other sites More sharing options...
ratdude747 Posted July 1, 2022 Author Share Posted July 1, 2022 In my experience coils are binary - they work or they don't. But in your case it appears the spark was arcing inside the coil when the cylinder pressure came up enough to make jumping in the coil easier than jumping across the plug's gap. In that case you could back off the throttle and keep driving. But if the MSD fails I'll bet it FAILS. So it might be wise to have a spare. However, coils are pretty common so you should be able to get one at any parts store - if you can get to one. I'd need to decide on that. Do I go for a stock Motorcraft or another "High voltage" coil from a different brand? I've seen a few other options... Link to comment Share on other sites More sharing options...
Gary Lewis Posted July 1, 2022 Share Posted July 1, 2022 I'd need to decide on that. Do I go for a stock Motorcraft or another "High voltage" coil from a different brand? I've seen a few other options... Do you have a high performance engine that revs well beyond the factory specs, or a basically stock 300 six? Remember that you have a system - the module sinks the current needed to charge the coil. So if you replace the coil with one that has lower impedance then the module has to sink more current. And it gets hotter. Is that enough to cause it to fail? You won’t know until it fails or the end of time. Link to comment Share on other sites More sharing options...
ratdude747 Posted July 3, 2022 Author Share Posted July 3, 2022 Do you have a high performance engine that revs well beyond the factory specs, or a basically stock 300 six? Remember that you have a system - the module sinks the current needed to charge the coil. So if you replace the coil with one that has lower impedance then the module has to sink more current. And it gets hotter. Is that enough to cause it to fail? You won’t know until it fails or the end of time. True. Although the heatsink should help a bit. If it blows, I'll go back to a stock rated unit. ---- The jury's out on performance. I could hold 70-75mph on cruise on flats... but overpasses and hills lugged the engine, requiring a forced downshift. Criuse was shoving the gas enough trying to make it go/downshift that I was losing vacuum and my A/C got sent to defrost (must have a leak or a bad check valve ). While I could add more TV cable tension, my fear is that in doing so (based off past experience) it'll refuse to upshift without downshifting and upshifting manually. Not sure if that's just a non-electronic AOD quirk or if there's something sketchy in my valve body... or if my engine just sucks? Funny enough, on a topoff, I found that I nearly got 18mpg. So I am getting good economy, it's just a bit physically taxing to make it work. Honestly this is an issue it's never fully gotten past. This is on par with the best I've ever had it run... Link to comment Share on other sites More sharing options...
ratdude747 Posted July 3, 2022 Author Share Posted July 3, 2022 True. Although the heatsink should help a bit. If it blows, I'll go back to a stock rated unit. ---- The jury's out on performance. I could hold 70-75mph on cruise on flats... but overpasses and hills lugged the engine, requiring a forced downshift. Criuse was shoving the gas enough trying to make it go/downshift that I was losing vacuum and my A/C got sent to defrost (must have a leak or a bad check valve ). While I could add more TV cable tension, my fear is that in doing so (based off past experience) it'll refuse to upshift without downshifting and upshifting manually. Not sure if that's just a non-electronic AOD quirk or if there's something sketchy in my valve body... or if my engine just sucks? Funny enough, on a topoff, I found that I nearly got 18mpg. So I am getting good economy, it's just a bit physically taxing to make it work. Honestly this is an issue it's never fully gotten past. This is on par with the best I've ever had it run... Oh, and I also shot fresh pics. I posted them to facebook, so I better post them here too! Link to comment Share on other sites More sharing options...
Gary Lewis Posted July 3, 2022 Share Posted July 3, 2022 Oh, and I also shot fresh pics. I posted them to facebook, so I better post them here too! What gearing are you running? The OD ratio on an AOD is quite high, so if you are running 3.0 gears the engine is hardly turning on the highway. But it looks pretty under the hood. Link to comment Share on other sites More sharing options...
ratdude747 Posted July 3, 2022 Author Share Posted July 3, 2022 What gearing are you running? The OD ratio on an AOD is quite high, so if you are running 3.0 gears the engine is hardly turning on the highway. But it looks pretty under the hood. The stock 3.08. The high altitude version got 3.55's. There was another thread on this where it seemed the issue is my engine not behaving right by not having enough bottom end. Then again, in OD at 65mph it's only turning 1500 or so... Supposedly I should be doing great there but in reality it struggles. Edit: about to make a 3 hour drive home in it. Gave the TV cable a few additional notches (1/8"?) of tension. Link to comment Share on other sites More sharing options...
Recommended Posts