1990 Ford F150 OBS Rough Idle, Fast Idle, Hard Shifting - Fixed for under $1.00

[@tedcorey3054]

I have a '90 150 Lariat 4x2 302 aod , had the trans rebuilt , lasted a couple years (light use) went again . I had the same problem with every week another issue . It's been sitting 6 or 7 years now , I need a truck so I might try again . I hope I don't have to solder anything , because my soldering skills aren't great . It was nice to one running .

[@CarsWithCory1]

I sure hope you can get it going again!

[@drunkingsailor2359]

750rpm standard, sometimes that so called idle screw on throttle body might have been adjusted and might need some correction in order to allow the iac to do it's job.

[@CarsWithCory1]

Thanks for sharing, I’ll have to check that out. This fix improved the condition but it didn’t solve everything. It does idle better now and shifting gears is night and day.

[@PhunkBustA]

one good tip i can give u with ur soldering is you should use a chisel tip, it'll have more heat capacitance and itll make thing go a bit smoother

[@CarsWithCory1]

Thanks for the tip (pun intended). I need to invest in new soldering equipment. All of mine is old and worn out!

[@JosephO1968]

Did you pull codes? My 95’s PCM problem manifested as just randomly shutting off in traffic (yay). The code it was throwing was something like “PCM memory test failed”

[@CarsWithCory1]

I probably should have but I jumped in and started soldering 😁

[@mikeceli]

Interesting! How about a Link to the Ebay Caps?

[@CarsWithCory1]

These are the ones I bought. Price has gone up a bit. www.ebay.com/itm/285196645181?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=xoYngVoKTuO&sssrc=4521899&ssuid=jmlzeliuqek&var=&widget_ver=artemis&media=COPY

[@mikeceli]

@@CarsWithCory1 Thank you!

[@murphytoadster9864]

Gonna blow a head gasket with you temp that high. I have a 1990 and a 1991 and they run NOWHERE near the middle. And yours is showing .75😮.. hopefully you just have a bad sensor. On my trucks at full temperature I'm 1/4

[@CarsWithCory1]

Never even noticed it. It doesn’t normally run that high. Thanks for pointing that out, I’ll give it a look over before I drive it next. This one doesn’t get driven much.

[@jimallen1485]

Not to be mean... but, your soldering skills need work Thanks for the repair tip.

[@CarsWithCory1]

Could you recommend another channel or video that shows better technique for the viewers? I wished I had a smaller tip handy and my variable temp iron didn’t want to work this particular day. That said, I’m a novice at best when it comes to soldering.

[@HD24680]

I noticed a few people asking about the capacitors. There are two 47uF 16volts, and one 10uF 63volt. Make sure you get caps with a temperature rating of 105 degrees Celsius. Get quality caps so you don’t have to do this again soon. Panasonic, Rubycon, Nichicon are quality brand names. And if you see corrosion under those caps from the leakage, make sure all of that gets cleaned off. A qtip and alcohol works. Be careful so you don’t damage any of the very thin traces (the places the current flows) and also make sure they have good continuity on both ends of the trace if you find yours look damaged. Quite common under leaky caps and just replacing the caps will not solve all of your problems.

[@Blackford86]

What made you lead to the ECM? I would’ve probably thought bad plugs or wires.

[@CarsWithCory1]

That’s a great question! Distributor cap, plugs, and wires had all been recently replaced. I had been diagnosing the two idle issues and shift issues independently and getting nowhere. I described the problems to my uncle who is a retired mechanic and owns a few of these trucks. He pointed me to the ECM.

[@Blackford86]

Good on your uncle pointing you in the right direction

[@Blackford86]

Have you done any transmission work on this truck?

[@CarsWithCory1]

@@Blackford86 no transmission issues, I’ve been lucky so far. It shifted so strangely before the ECM fix I was concerned I’d be in there soon but all of the strange shifting behaviors went away after the repair. I do need to do a fluid/filter on it at some point. This truck only gets about 10 miles a month put on it.

[@timkis64]

my 90 ford has been the most reliable vehicle i ever owned.back when ford still give a crap about quality & dependability.sadly, they are gone forever from ford products.replaced by greed & short term junk.

[@CarsWithCory1]

When you find a good one you gotta hold on to it!!!

[@late0404]

Man idk about that the new super duty’s are the most reliable trucks on the road

[@CarsWithCory1]

@@late0404 I had a 2014 with the diesel and it was amazing!

[@yaboidustin2447]

​@@late0404😂😂😂😂😂😂

[@late0404]

@@yaboidustin2447 your laughing but you know it’s true!

[@betavirus11]

boy almost lost a 10mm. lol

[@CarsWithCory1]

Hahahaha. In the moment I was thinking the same thing!

[@trustme7731]

I just changed my idle air control on my '90 F350 5.8 due to the engine dying with the AC on. I found the IAC was very clean and the shaft moving freely. BUT, the solenoid was not working . Problem solved. I suspect it can also account for unnecessary high idle too. I suggest you replace it and see or at least test the solenoid.

[@CarsWithCory1]

@@trustme7731 Thanks for sharing. I unplugged mine while it was running and the RPM dropped way down so I took that as it’s working but still wonder about it.

[@DarthSpunch]

My 91 f150 inline 6 is idling high at 1000 rpm and after revving it goes right back down to that. And it jumps down then right back up. I was told to check the IAC valve because it might be bad. Not sure how to go about it. Any tips?

[@CarsWithCory1]

I checked the IAC first on my truck. What you can do is start up the truck and while it’s running unplug the wire harness to the IAC. If the idle drops super low and/or the engine stalls, the IAC is working. If there’s no change it’s probably bad.

[@murphytoadster9864]

A good Coolant temp sensor supposedly will lower your idle. Maybe yours is bad

[@CarsWithCory1]

The way this truck is it could be a sensor or almost anything else. Seems like every time I drive it there’s something slightly wrong with it 😂.

[@murphytoadster9864]

@@CarsWithCory1 EGR vacuum solenoid changed both my truck and my bronco. Has way more power no rough idle smooth acceleration and more balls

[@CarsWithCory1]

@@murphytoadster9864 I think there are still problems with the idle circuit of this truck. It’s way better after this ECU repair but still not perfect. Thanks for the tip.

[@coreysmith4085]

I have a 1989 f350 that is having similar issues I have to drive it like a manual to get it to shift and after driving 25 and stopping at a red light or stop sign it wants to surge. Any thoughts as if it could be this same issue?

[@CarsWithCory1]

It could be contributing to the problem but if yours is not shifting at all without manually shifting I’d say you probably have another issue. Mine would shift on its own with no stalling or surging, but always too early upshift and too late downshift. It would quickly get to overdrive even at low speeds and wouldn’t downshift until I basically floored it.

[@UFOGHOSTHUNTER]

Great job. A ton of FoxBody Mustang's have the exact same issue.

[@CarsWithCory1]

Thank you! Now that I think about it, I know someone with a fox. That one is a manual but the idle bounces around. Maybe I can get his car on the channel and get a part 2.

[@OverTaxed42Long]

Skip to 4:50 for the start of the info you are looking for.

[@51sicboy]

Keep the old ones running, the new ones are overpriced and turns us into goooo. LOL!

[@CarsWithCory1]

I absolutely agree. If you check out my other videos I have a series on my 2010 Expedition daily driver I’ve put a lot of miles and $$$ into to avoid buying anything new!

[@steve8189]

Good video, am saving for a future project. Interestingly, I have been spinning about the extremely hard shifts that would mysteriously go away. Very long story, no real guidance in following the codes I pulled. There is still an issue and your solution will be on my future attempts to correct the issue. In the meantime, I also figured out that in troubleshooting my issue I finally read in a forum that the codes, even though cleared using my reader, were still having an effect in the truck UNTIL I disconnected the battery. It is a 94 f150 5.0, a truck used temporarily and for plowing. What triggers it back into hard shifting is going over 60mph! After confirming this condition, my plan is to keep it under 60, and so far so good, driving for weeks now!!! The battery disconnect was really causing inconsistent "results" in repair attempts. I also noticed that in your case shifting was smooth after the capacitor replacement AND a battery disconnect.

[@CarsWithCory1]

@@steve8189 That’s so strange. Thanks for sharing, your dialogue will probably help others diagnose issues with their own trucks!

[@steve8189]

@@CarsWithCory1 Thanks, and I hope so!

[@WillLynn-c2p]

Outstanding

[@martrelleadams5406]

Have a 91 Lariat regular cab ! Community has been awesome went answering questions.

[@CarsWithCory1]

@@martrelleadams5406 Great trucks and fairly easy to work on. Definitely a lot of knowledge out there on them for sure.

[@royhennagir7685]

Thank you!

[@donaldfrederick1557]

Brick nose not OBS

[@CarsWithCory1]

They need to start teaching a class on Ford pickup nickname identification in grade school.

[@juventinocarra5445]

Hey boss can you post link on those capacitors.thanks on taking your time on this issue got the same issue I suspect thanks again.

[@CarsWithCory1]

Here is the set I bought off eBay. www.ebay.com/itm/285079885645?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=xoYngVoKTuO&sssrc=4429486&ssuid=jmlzeliuqek&var=&widget_ver=artemis&media=COPY I know they are more than $1, I don’t live near any electronics supply stores so I had to pay more to order them online.

[@gerry-p9x]

U got ripped of. Ha ha. I'd pick up a spare ECU FROM JUNK YARD TEST. IT AND KEEP AS SPARE😊😊

[@Belzon1]

The ecu's for these Ford's are for their exact model. 4.9L with manual won't fit a 4.9 with an auto and sure won't work for a 5.0 or 5.8. Every transmission and engine combo had a different ecu

[@CarsWithCory1]

@@Belzon1 thanks for sharing. I would have guessed they would be similar by engine but wouldn’t have thought about different transmissions or options.

[@gerry-p9x]

Yeah I'd put the word out for a comparable. ECU. In yards and see if available. ​@@CarsWithCory1

[@travdasav468]

what do each of the capacitors control?

[@CarsWithCory1]

@@travdasav468 I don't know specifically. Capacitance is stored energy so they feed a circuit voltage when it needs it. The only thing I can gather is the one I replaced had something to do with the transmission because it shifts way better now.

[@HD24680]

If you haven’t done so already, you NEED to get back into that module and replace the other two caps. Additionally, the leakage from the one you did replace has damaged the small traces near it. Those will need to be checked for continuity and may need jumpers from the end points if the traces are that bad. That is how you fix traces that are that small, with wire jumpers. I could see they looked corroded to a point where you probably have lost some vehicle component controls from that ecu. That leakage becomes an acid that eats the copper traces away. They turn dark like yours did when that happens. As far as your soldering, when you bring the soldering iron to the pad and the lead, leave the soldering iron on it for a few seconds longer with the solder. Wait for the solder to completely melt and leave the iron there for a few seconds more so the pad and the lead get hot enough to allow the solder to attach to both. Don’t continue to add more solder. Once the solder melts on both, it will form a cone. When you kept putting more solder on the spot and kept pulling the gun away, that’s why it beaded up on you. But anyway, once you are in that thing, always replace all of those electrolytic capacitors. They have likely developed a high ESR value after this much time, and that is not something you can visually check for. Additionally, if they start leaking too, you will have more damage to the traces. 🙂

[@CarsWithCory1]

@@HD24680 Great advice, thank you! I'll be doing more work on the truck this fall and plan to get back into the ECU. Thanks for the soldering tips, I do very little board soldering, mostly wires.

[@johnscott2076]

Gotta change your ECU fluid periodically 😅

[@morgansword]

I feel dumb asking a question like mine. I used to mechanic, but never worked on electronics. I loaned my explorer to a kid and he brings it back a month later with it out of oil, did have maybe a pint in it. We replaced the oil and there is no knocking sounds, no anything out of the ordinary except for the pressure is very low. It starts and runs well, it is not a high mileage rig and it is a 95 model with the 4.0 engine. Is the ECM have anything to do with oil pressure readings

[@CarsWithCory1]

No problem with asking questions, it’s how we all learn! Diagnostically I’d expect the low oil pressure is due to the wear the engine endured with low oil. Must not have caused enough damage to create any knocks or noises. I’m not entirely familiar with how the ECM integrates to the oil pressure system in that vehicle. I’m guessing it may only place a diagnostic code or put the vehicle in limp mode if it sees a problem. That is totally a guess, it may not be connected at all. I wouldn’t expect the ECM is causing the low oil pressure reading, If the oil was that low I bet the bearings are super worn and life expectancy of that engine would be very low.

[@morgansword]

I also thought the same as you. I want to thank you for responding@@CarsWithCory1

[@CarsWithCory1]

@@morgansword No problem! Good luck with the Explorer!

[@tdotw77]

If it was run low on oil, the low oil pressure is from worn crank\main bearings. You said a pint was in it? Is that what showed on dipstick, or what drained out upon doing oil change? If only a pint came out of oil pan, that engine is a perfect boat anchor candidate right now. I'd say the kid was probably beating on this thing too but idk for sure? Was there an oil consumption problem previously(before getting loaned out)? If I were you and the rest of this vehicle is in great condition, start looking for a nice lower mileage motor from a junkyard online right now. Probably $3 -4k should get you an engine & installation r&r. Unless you & a friend can tackle the project. It's not hard but you do need an engine lift, jack, j.stands & of course hand tools - sockets, wrenches, etc(really don't need any specialty tools or a lift tho). I know a guy w\ an Explorer(exploder) who never changed his oil, nor even checked it for that matter. So the thing smoked itself on a thruway trip & seized up due to lack of any oil. I gave my buddy a hand putting a junkyard engine into it. Iirc, i think it was all done for under $3k (~$2200engine + $650labor + fluids), which is not too bad compared to buying a new one @ $500 --$1000/per month! 😮😢👍🏻🛠️🔧🔩🤔🤷🏻‍♂️🚗🚐🚦⛽🛢️🚧