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22re “invisible turbo” symptoms
Recently posted about similar issue but I feel like the problem has evolved enough to warrant a new thread and hopefully bring some closure to at least 15 dead end threads I read describing my same issue. I think the easiest term for what the truck is doing is the “invisible turbo” symptom. What I’ve noticed in my truck and other trucks across the board is that they will have a rough idle around 500rpms and run rough/seemingly miss with little power until the RPMs reach about 3500 and then the normal power surges in hard. Hence the turbo reference. The odd thing is that in my case and the other posts, the issue is intermittent. Some folks report this issue coming around once every year, some almost all the time. My truck first did the invisible turbo thing 5 months ago for a day and then it just went away. In the last week the issue has become constant and happens about half the time im driving the truck. Once the RPMs are above 3500, the truck has full power. The truck can cruise at 80mph with no feelings of loss of power. As as far as my truck goes, it’s an 87 4runner with the 22re, MT. 220k Miles. The fact that there is no CEL on is really strange to me. There is a bulb in the display, and it flashes once per normal on start up. So far I have 1.checked for vac leaks(found none) 2. Unplugged spark plug wires during engine running. Engine stumbles more when wires unplugged as anticipated. 3. replaced plugs(old ones looked a little oily, but new plugs did nothing and the new plugs look chocolate with no fouling after 100 Miles) 4. Replaced wires(used dialectic grease) and cap/rotor 5. Replaced O2 sensor with Denso unit 6. Replaced TPS sensor, the original Toyota unit was slow to return to neutral. I calibrated the TPS with a feeler and OHM meter. 7. Inspected TB and it was not profoundly dirty. The valve has no grime on it and operates normally through range of motion. The issue persists. I’m a little stressed because I live full time in my 4runner. It kinda sucks when your house is broken. My next thoughts from reading other posts are... Check timing(don’t think it’s this due to sometimes it runs great) Replace fuel filter Replace injectors Check wiring harness to injectors for corrosion Replace fuel pump Check yellow EFI relay near right speaker for crud Check coolant for air bubbles Replace coolant sensor Replace fuel pump If y’all have any other ideas on what to do I would be very grateful. At this point I can’t just take the truck to a shop. Everything I own, including were I sleep is in my truck! Thanks y’all, Sam |
none of the things in your list will solve it. it may, in fact, be a timing issue with a root cause buried in the ecu which allows way too much advance in some closed-loop situations. There was an internal bulletin for Toyota factory technicians back in the mid 80’s about a similar issue with 22RE engines. The issue was an internal programming problem with the ECU. Since the ECU advances the timing according to engine RPM, throttle position etc., sometimes it would freak out and give it too much TOTAL advance on accel and partial throttle. It would give it 40+ degrees total advance instead of the 28 degrees (those are random numbers I pulled out of the air, not the ACTUAL numbers, just using them as an example). For a while during the time when owners of these trucks actually brought them to a dealer, one of their fixes was to install a reman ECU (that’s why you see some of the ECU’s in the 85-87 model years have a “-84” after the part number on the sticker, it means remanufactured). It didn’t always help. One fix that was recommended in another, later year, bulletin was to set the base timing at 3 degrees instead of 5 (which would translate to 10 degrees without the ECU jumped). If that didn’t help? They recommended 2 degrees base timing. I know it sounds counter-intuitive to retard timing to improve performance, but about 50% of the time, it would solve the problem. |
Originally Posted by Sam Latone
(Post 52406726)
Recently posted about similar issue but I feel like the problem has evolved enough to warrant a new thread and hopefully bring some closure to at least 15 dead end threads I read describing my same issue. I think the easiest term for what the truck is doing is the “invisible turbo” symptom. What I’ve noticed in my truck and other trucks across the board is that they will have a rough idle around 500rpms and run rough/seemingly miss with little power until the RPMs reach about 3500 and then the normal power surges in hard. Hence the turbo reference. The odd thing is that in my case and the other posts, the issue is intermittent. Some folks report this issue coming around once every year, some almost all the time. My truck first did the invisible turbo thing 5 months ago for a day and then it just went away. In the last week the issue has become constant and happens about half the time im driving the truck. Once the RPMs are above 3500, the truck has full power. The truck can cruise at 80mph with no feelings of loss of power. As as far as my truck goes, it’s an 87 4runner with the 22re, MT. 220k Miles. The fact that there is no CEL on is really strange to me. There is a bulb in the display, and it flashes once per normal on start up. So far I have 1.checked for vac leaks(found none) 2. Unplugged spark plug wires during engine running. Engine stumbles more when wires unplugged as anticipated. 3. replaced plugs(old ones looked a little oily, but new plugs did nothing and the new plugs look chocolate with no fouling after 100 Miles) 4. Replaced wires(used dialectic grease) and cap/rotor 5. Replaced O2 sensor with Denso unit 6. Replaced TPS sensor, the original Toyota unit was slow to return to neutral. I calibrated the TPS with a feeler and OHM meter. 7. Inspected TB and it was not profoundly dirty. The valve has no grime on it and operates normally through range of motion. ... Check timing(don’t think it’s this due to sometimes it runs great) Replace fuel filter Replace injectors Check wiring harness to injectors for corrosion Replace fuel pump Check yellow EFI relay near right speaker for crud Check coolant for air bubbles Replace coolant sensor Replace fuel pump http://i63.tinypic.com/20abbky.jpg Several hundred miles, lots of hours. https://cimg8.ibsrv.net/gimg/www.yot...2f68a4efb7.jpg Several hours, maybe 50-100 miles (I would have to search..) Oily plug(s) before, and chocolate now. Pictures would of helped alot here. Wet oily? Next up is idle and base timing. Idle speed and ignition timing are linked. This means you set the idle RPM speed (spec is well over 500), then adjust the distributor, then go back and verify the idle speed. If the idle speed went out of spec you must reset it then check/set the ignition timing. (You may wind up repeating this cycle a few times!) Pulling plug wires only identifies a completely non-firing cylinder in most cases (think bent/stuck valves), not a slight missfire. There is a resistance spec for high-tension spark wires. Did you check the old ones before you replaced them, what about the new ones? Double, tripple check the air intake hose for leaks and cracks. Your idle is low and rough, this could be the fuel pump turning on and off. Which valve are you referring to? Do you mean the throttle plate, or are you talking EGR functionality. Along this same line, check the EGR isn't sticking open. The one way that comes toind is to place a bit of soda can between the in-port on the back of the plenum chamber. |
Originally Posted by wallytoo
(Post 52406750)
none of the things in your list will solve it. it may, in fact, be a timing issue with a root cause buried in the ecu which allows way too much advance in some closed-loop situations. |
Originally Posted by Sam Latone
(Post 52406726)
Recently posted about similar issue but I feel like the problem has evolved enough to warrant a new thread ... Thanks y’all, Sam https://www.yotatech.com/forums/f116/1987-4runner-rough-idle-cold-start-no-power-305387/ What we have here is a very good example of why it is good to keep issues and diagbostics to one single thread.. I wouldn't have told you to block off the EGR valve, for example. Sure I might have forgot by page four but the information would be there if I went back and reread everything. Being in different threads I had to WORK to try and help you. Pictures, video, audio recordings, even bad ones can be of use. Help us help you sir.. So which coolant sensor(s) exactly did you change? Did you test the new one, and/or the old one to FSM specs? Did you verify this signal reaches the ECU intact and reliably? From here what I see is a wet (fouled) sparkplug that dries up with some heat build up. It maybe still leaking after warmed up and vaporizing. The next step is to determine is this oil, fuel, coolant or a red herring. You've not eliminated the ultimate basic either. Good ground is imperative to EFI operation, especially on technology of this era and age. This relates to your odd gauge behavior reported earlier. There are multiple ground points involved, one in the cab for gauges, one on the intake for the ECU and efi sensors, and the primary chassis ground on the fender which supplies the ignitor. Spend an hour or whatever and make sure these are all freshly cleaned and tight with bright shiny metal on wire and mount points. (Probably some other stuff I'm missing.) |
What about the AFM mechanically hanging up? Have you inspected its operation?
Here's a link to good information about the EFI system. https://people.well.com/user/mosk/EFI1.htm |
My neighbor's 93 pickup with the 22re had some similar symptoms. But it seemed to only happen in first gear, but at the same time, he drove it like a madman and probably never dropped under 3500 rpm outside of starting in first. He suspected it was a vacuum leak. I changed the head gaskets out in my 3vze, and he wanted me to do his also. So I replaced his head gasket, which looked to be leaking from the rear cylinder. At the same time, I did the EGR and pair valve delete. He did have 2 tears in the air duct to the throttle body that we half assed replaced with one from a 3VZE and a spacer with duct tape. After I got everything back together, he didn't have that problem anymore. Until the duct popped off, and it acted the same again.
So I would say check that air duct for any tears first. Unmetered air going into the engine can screw up the AF ratio. Next bet would be to do the EGR delete if you are comfortable with that, and you don't have to run through emissions for registration. The other step would be to do a compression test to see if the head gasket is leaking. If you do need to change it out, it's probably one of the easiest head gaskets I've ever done. I had the head out in under 2 hours, and probably could have had it back in within 3 hours after cleaning up the piston heads and the bottom of the head, but his timing chain guides were broken, so I had to pull the front timing cover off and wait for parts, so it ended up taking a few days. Technically, you should have the mating surface of the head and the valves all checked and cleaned up prior to reinstalling, but my buddy and I are both planning on engine swaps in the near future, so we just needed "good enough for now". |
Its possible the igniter is failing. The igniter is the middle man between the ecu and the distributor and controls when the ignition coil fires. I would all so closely inspect the wiring between all of the ignition components. These truck are getting very old and the harness are brittle.
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Originally Posted by Co_94_PU
(Post 52406780)
https://www.yotatech.com/forums/f116/another-idle-issue-298604/
https://www.yotatech.com/forums/f116...-power-305387/ What we have here is a very good example of why it is good to keep issues and diagbostics to one single thread.. I wouldn't have told you to block off the EGR valve, for example. Sure I might have forgot by page four but the information would be there if I went back and reread everything. Being in different threads I had to WORK to try and help you. Pictures, video, audio recordings, even bad ones can be of use. Help us help you sir.. So which coolant sensor(s) exactly did you change? Did you test the new one, and/or the old one to FSM specs? Did you verify this signal reaches the ECU intact and reliably? From here what I see is a wet (fouled) sparkplug that dries up with some heat build up. It maybe still leaking after warmed up and vaporizing. The next step is to determine is this oil, fuel, coolant or a red herring. You've not eliminated the ultimate basic either. Good ground is imperative to EFI operation, especially on technology of this era and age. This relates to your odd gauge behavior reported earlier. There are multiple ground points involved, one in the cab for gauges, one on the intake for the ECU and efi sensors, and the primary chassis ground on the fender which supplies the ignitor. Spend an hour or whatever and make sure these are all freshly cleaned and tight with bright shiny metal on wire and mount points. (Probably some other stuff I'm missing.) I made the mistake of taking my truck to a shop because I became overwhelmed, I feel defeated. They told me the AFM was bad. I didn't get a chance to talk to the tech before they closed, picked up my truck, and proceeded to find out what that meant. I proceeded to do what I should have done in the first place. On inspection of the AFM, it appears to function normally in a mechanical sense. The flapper moves freely without issue or sticking spots. The interesting thing is that when I OHM tested it, I had some really strange readings during the E2/VS test. The spec is between 20-400 OHMS. The first test showed 431 OHMs, out of spec but not by that much. The other tests checked normal. During the flapper open, flapper closed test I noticed something really odd with E2/VS. When the flapper is opened all the way the meter showed 300 OHM(normal) consistently but when the flapper was returned to closed position I would get a different resistance reading every time I cycle the flapper open and closed. This means that the resistance in the E2/VS circuit is variable. I picked up a re-manufactured AFM and ran the same tests. This AFM shows 130(closed) and 300(fully open) OHMs every time with consistency. It stands the reason that if the resistance between E2/VS is variable, then the computer is getting variable voltage(air readings) and causing things to go haywire. The truck is idling a little rough still with the new AFM but I have not experienced the invisible turbo symptoms again, YET. I have the day off to focus on truck stuff so I'm going to continue diagnosing the rough idle, even if the misfire under load is gone. In the FSM under troubleshooting for hard start/rough idle/misfire the common denominators in order are...ignition, then the coolant temp circuit, then AFM, then TPS. I can see I've been doing some stuff backwards. Seeings how I have a new AFM and new TPS, the order of business today is. Clean grounds Check fuses Check ignition system Check coolant temp sensors Jump the fuel pump just for giggles, its easy, and listen for consistent whirring noise https://cimg8.ibsrv.net/gimg/www.yot...dea9900de8.jpg |
Posting the test results of my engine coolant temp sensor and the start injector time switch tests. I posted a nice video that explains how to do this and cross referenced it with the pages in the FSM. I performed this test while my sensors were on the vehicle.
cold start injector time switch 70 degrees (cold) 30 ohms within spec 105 degrees (hot) 55 ohms within spec temp sensor 70 degrees (Cold) 2k ohms within spec 180 degrees (Hot) 522 ohms within spec Also after jumping the fuel pump I could hear that it whirs in a constant way but ever 15 seconds or so the pitch will change ever so slightly and then return back to the regular timbre. Can anyone chime in as to if this is normal or abnormal fuel pump behavior? Thanks. |
Also, I can not for the life of me find a FSM PDF that applies to the 1987 4Runner. Until now I've been using the the 89-95 FSM linked below. Its worked well up until now. Im wanting to run through the 10 or so system tests at the ECM plug ins to do a check well while my ECM unbolted. My ECM and the diagram for the ECM in the FSM are not lining up.
Thanks |
Try this for the FSM I think it might work. 86-89 FSM
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Thank you! It’s downloading now. Further update I set the timing to 5 degrees. The timing was off the scale retarded and then went to 2 degrees jumped. Set timing to 5 degrees per a 22re Performance video. Also I have cleaned all 4 of the ground points and they were disgusting. The truck now seems to be idling well. Time will tell If the poor idle/stumble and misfire under load until 3500rpm returns |
The chunkiness of the plugs is disturbing me, those little deposits cause hot spots, hot spots cause misfires of the pre ignition type, pre ignition is picked up by the ECU via the knock sensor.
I don't recognise the markings on those plugs but I'd wager from the electrode shape they are not the correct plugs. These early efi/TCCS computers and engines do not like plugs other than those specified by the manufacturer, you will find lots of posts about using the correct plugs solving misfire problems. .. Your faulty vafm sounds like someone tried to open the plug connector housing which will tear the connectors off the circuit board. It's repairable.with a soldering iron and some patience. Fix it and keep it on the shelf for a spare, unless it got binned or sent back for CORE. .. You seem to be on the right track, keep at it. If you're love of Toyota is proper serious start looking for the print edition of the correct years FSM it's worth its weight in gold. These early system.designs went thru various changes year to year and in some cases even in the same model year. |
Originally Posted by Naked Runner
(Post 52407675)
Try this for the FSM I think it might work. 86-89 FSM
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I will keep my eyes peeled for an 87 FSM. At this point it’s impossible for me to do voltage tests on the ECM. An hour before is finished my work, I took off the radiator cap to check for full coolant. It was full. Once the truck got back up to idle I noticed the cap had a trickle of coolant coming from under it. Never happened before. Wonder if the blew out when i took it off. Guess ill I’ll be picking up a new rad cap and new plugs tmro. Anyone ever seen this happen? Search came up dry. |
I have no idea what that odd wire coming off of the two wires going in to the distributor sensor is. Got to love previous owners. Any idea what that is? |
Pic isn’t showing up. Standby |
ECU testing
I don't recall a lot of wires moving around here.
Start another thread, titled similar to, "1987 ECU diagram" There is probably someone willing to take a photo of that page for you. It's worth noting some times the diagram shows the view from the end of the connected and sometimes the back of the connector. You can tell which by locating the battery power inputs, or counting pins on the plug. You need to be "looking at it correctly".. Another option for diagrams is the Autozone website, they have alot of these available you can find them via Google or registering in the repair help section. |
Originally Posted by Co_94_PU
(Post 52407709)
I don't recall a lot of wires moving around here.
Start another thread, titled similar to, "1987 ECU diagram" There is probably someone willing to take a photo of that page for you. It's worth noting some times the diagram shows the view from the end of the connected and sometimes the back of the connector. You can tell which by locating the battery power inputs, or counting pins on the plug. You need to be "looking at it correctly".. Another option for diagrams is the Autozone website, they have alot of these available you can find them via Google or registering in the repair help section. |
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