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Juan Crespo
Juan Crespo, Tech Trainer
Category: Toyota
Satisfied Customers: 1513
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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4Runner: Have an 87 4Runner, injectors are not firing. Grounds

Customer Question

Have an 87 4Runner, injectors are not firing. Grounds have been checked. Need 22RE expert.
Submitted: 1 year ago.
Category: Toyota
Expert:  Juan Crespo replied 1 year ago.
Hi there. Welcome to our site. The ECU needs to see a couple of input signals or the injectors won't be turned on, these are the IGF and the NE signals: The IGF is the signal that tells the computer that there is spark to the spark plugs. The NE signal is an rpm input signal from the distributor pick-up coil that lets the computer know the engine is turning over, if this signal is not there the injectors will not fire.First, turn ignition on and check for system voltage at ECU connector A, terminals 1 and 8 (Black wires on both). If OK, check for system voltage at injectors 2 and 4 (Blue wires) and 1 and 3 (Yellow wires). If OK, turn ignition off and check distributor pick-up coil resistance (see attached graphic). If resistance not 140-180 Ohms, replace the distributor assembly - Nippondenso distributors used on 22RE systems are not serviceable. Kindly accept and rate my answer now if you think the information I've provided has helped you solve your issue. Otherwise, please reply. Best Regards.
Customer: replied 1 year ago.
My ECU pinout has IGf and Ne the middle large plug at 5 and 9.
Expert:  Juan Crespo replied 1 year ago.
Unless you have an oscilloscope for testing the actual NE signal at the ECU, testing for resistance at the ECU would result in inaccurate readings. It's easy to get sidetracked when testing these issues. My advise as an experienced Master Technician is to stick to the simple procedures. Please follow my instructions and check for system voltage at the ECU and injectors, then test pick-up coil resistance. Please let me know what you find. Best Regards.
Customer: replied 1 year ago.
IGf @ 201v ?? Ne @ 12.7 Blue & yellow both at 7.27 Coil @ 165 ohms ( this was checked on female plug with ignition off correct?)
Expert:  Juan Crespo replied 1 year ago.
You've lost me completely. Please understand that we are not trying, nor do we need to measure voltages for the IGF and NE signals and. All I need you to do is perform the checks that I indicated. Only when I have the results of those tests will I (or any other expert) be able to help you solve your issue. In other words, you'll be doing both of us a big by answering these questions with a simple YES or NO:With the ignition on, is there system voltage (more than 10 volts) at ECU connector A, terminals 1 and 8? YES or NOWith the ignition on, is there system voltage at the Blue wire going to injectors 2 and 4? YES or NOWith the ignition on, is there system voltage at the Yellow wire going to injectors 1 and 3? YES or NOWith ignition off and distributor disconnected, are there 140 to 180 Ohms resistance at the pick-up coil? YES or NOBest Regards.
Expert:  Juan Crespo replied 1 year ago.
I need to log off for dinner. I'll be back online later tonight.
Best Regards.
Customer: replied 1 year ago.
Terminal 1 - yes
Terminal 8 - no
Blue to injector - yes
Yellow to injector - yes
Ohms at Distributer plug - 165
Expert:  Juan Crespo replied 1 year ago.
We seem to have a problem with no system voltage at ECU terminal 8. Since it is the same circuit that supplies voltage to terminal 1, the only logical explanation would be a broken wire or splice. To confirm, turn ignition off and disconnect ECU connector A; then, working from the harness side, check continuity between terminals 1 and 8. If no continuity, trace and repair an open in the Black wire going to terminal 8. If there is continuity, then you're either checking the wrong terminal or the ECU is shorted to ground. 165 Ohms resistance is within parameters for the pick-up coil; however, I would prefer to look at the signal on a scope screen. If you're interested, you could get a single channel scope that will work on your laptop on the internet for about $80; or one that will work off your Android smart phone for about $149. If need be, I would gladly show you how to use it. You'd be amazed with how much you can do with a scope when it comes to this type of issue. Best Regards.
Expert:  Juan Crespo replied 1 year ago.
Signing off for tonight. Will be back online tomorrow after lunch ET.
Customer: replied 1 year ago.
Apologies Sir. I must have been reading off of connector "C" thinking it was "A" as it would appear looking at the ECU pinout in the FSM. "A" I now understand would be on the right side of the ECU as that is where the 2 black "+B1" and "+B" wires are at terminals 1 and 8.
New readings:
Terminal 1 - yes
Terminal 8 - yes
Blue to injector - yes
Yellow to injector - yes
Ohms at Distributer plug - 165
Expert:  Juan Crespo replied 1 year ago.
Thank you for the update.It looks like the signal is there, just not getting to the injectors. Let's remove the tape and protective coating from the main harness between the intake manifold and the fuse box under the hood, you may notice Green corrosion on the wires in question where the mechanical crimp splice is made. If so, the best solution is to cut and splice in new wires. Please let me know what you find. By the way, have you pulled any codes from the system? Best Regards.
Customer: replied 1 year ago.
Cut into the harness a couple days ago to investigate condition of ground wire splice from ECU to injectors. Read about someone's experience with that on YotaTech. The ground wires were infact highly corroded. Cut, respliced and sealed.
I am getting codes 7 and 11.
Expert:  Juan Crespo replied 1 year ago.
OK. The one thing codes 7 and 11 have in common is TPS. If the ECU is seeing more than 4 volts from the TPS on start-up, it'll see it as a "clear flood" signal and won't open the injectors. Check the TPS signal with ignition on and engine off, it should be less than 1 volt If not, we might be dealing with a bad TPS or throttle body. Best Regards.
Customer: replied 1 year ago.
Yes, 5v detected on Vcc. I have 4 terminals on my TPS
Vcc / VTA / IDL / E2
Here's then readings I got from them:
Vcc = 5v
VTA = 0
IDL = 0.1
Expert:  Juan Crespo replied 1 year ago.
OK. Leave the TPS connected and turn ignition on; then backprobe the connector with the voltmeter positive probe in the VTA terminal and the negative probe in the E2 terminal (see attached graphic). Voltage should be between 0.4 and 1.0 volt with the throttle closed; 4.0 to 4.9 volts with the throttle wide open. Please let me know what you find. Best Regards.
Expert:  Juan Crespo replied 1 year ago.
Got to take the family out to watch the fireworks show. I'll check on you again tomorrow after lunch.
Best Regards.
Customer: replied 1 year ago.
I was only reading 24mV to 30mV throttle open.
Have fun at the Fireworks. Happy 4th!
Expert:  Juan Crespo replied 1 year ago.
Will do. Thanks!
Expert:  Juan Crespo replied 1 year ago.
Had to come back early because of storms.
So, what is the voltage between VTA and E2 with the ignition on and throttle completely closed?
Couple of more things;
1- have you measured fuel pressure at the rail? - should be around 40 psi
2- will the engine start with starting fluid? - this will ensure we have spark
Be back tomorrow. Happy Fourth!
Customer: replied 1 year ago.
Voltage is 24mV between VTA and E2 with throttle closed.
Have not checked pressure at rail, I don't have that tool. But I did remove the upper plenum a couple days ago when I was checking the splices for those injector grounds and the fuel sprayed out like a geyser when I undid the cold start injector banjo bolt.
Engine will run with starter fluid as long as I keep spraying it.
Expert:  Juan Crespo replied 1 year ago.
OK. So we've got the VCC 5 volt reference signal coming in from the ECU to the TPS, but we're missing the VTA return signal from the TPS. Now, I hate to remind you, but you have to measure VTA by backprobing the connector while it is plugged in to the TPS, otherwise you're going to get almost zero (0) volts. Also, just to make sure, measure voltage from E2 to battery positive post; it should be more than 10 volts.Let me get a bit of history from you; when did this issue start? how did you discover the injectors were not firing? what was happening before?
Customer: replied 1 year ago.
Right now the battery is recharging at the neighbors. Down to 12v from all the test. Cranks the other day. I will investigate the TPS again as soon as I get my battery back this evening. But to confirm, yes, I did meter VTA by backprobing the connector while it was connected.
History:
The 4Runner has been doing this for the past month. I bought the truck a couple years ago from a hillbilly who had converted it to a 22R ( it was originally a Turbo).
After I got it to my garage at home, I began searching for EFI parts for it. Found a guy who was parting out the complete EFI system from his 87 (same year) 22RE Truck. I began to install, then life got in the way. Fast forward to 2 months ago. I started the process of completing the EFI rebuild, including cleaning out fuel tank and lines and making sure it was all flowing.
She wants to start. After a few cranks, the Cold Start Injector (I assume) does it's job and pumps a little fuel in, which causes it to fire up for a second or two, then cut right off.
I've hook a test light up to the injectors and there's voltage, but no pulse. The spark plugs are also dry.
One thing I'm wondering about is my ECU ( that came from the EFI donor).
It has the same part number as an ECU stamped 22RE, but mine is stamped "22R"? I'm concerned it's the wrong one, but the donor truck ran EFI with it, and some folks on the forums say the "22R" stamp is just a stamp, it's the same inside as one with "22RE" on it. Then some people say it has no circuitry for the injectors. I wish someone could clarify this for me.
Expert:  Juan Crespo replied 1 year ago.
Thanks for that update. Here are a couple more things for you to consider:A 22R ECU will not work on a 22RE system - different transistors, different fuel strategies.These injectors tend to get plugged-up and stuck if not used frequently
Customer: replied 1 year ago.
Why does it have the same part number if it's a different part? If you look up the part number on my ECU, it'll show an EFI ECU.
Expert:  Juan Crespo replied 1 year ago.
I can't answer the "why", but if you give me the part number, I can tell you if it is for carb or EFI
Customer: replied 1 year ago.
89661-35070
Expert:  Juan Crespo replied 1 year ago.
Thanks for that infirmation. That number ECU fits 1986-87 Toyota P/Up and 4-Runner with 22RE non-turbo EFI, so it should fit your truck. So far we know the TPS is shot (no VTA), but it's not in clear flood mode. Therefore it should not prevent the ECU from firing the injectors. That leaves us with...a potentially bad NE signal from the dist/igniter (possible but doubtful because resistance is 165 Ohms) low fuel pressure (possibly not up to the 38 psi needed to overcome injector pintle spring tension)plugged-up injectors stuck closed (possible)bad ECU (correct unit, but possibly shot driver/transistor)So here is what I would do;get a loaner fuel pressure tester from Advance or Autozone and test the systemif pressure more than 38 psi, remove injector rail assembly and activate each injector individually to see if they're working correctly. Replace if they don'tget a simple one-channel scope to test NE signal:If bad, replace igniter/distributor.If good, replace ECUreplace the TPS
Customer: replied 1 year ago.
I'll get those tools and work through that list.
Expert:  Juan Crespo replied 1 year ago.
Don't be afraid of the scope, it's just like a voltmeter. Let me know when you have it and I'll gladly work with you until you get the hang of it.While you're at the parts house borrowing the fuel pressure tester, you might want to get a cheap Noid lite to test injector pulse. The regular test light might not be giving you an accurate picture. Best Regards.
Customer: replied 1 year ago.
Ok, got the fuel pressure gauge and a noid light kit. All three of the main parts store in my town looked at me like I was asking to buy a monkey off the black market. I have a friend that owns a mechanic shop. I'm going to call and see if he would let me borrow one.
Expert:  Juan Crespo replied 1 year ago.
Yeah, I know. That's why it baffles me to see people going to a parts store looking for mechanical advice. If your friend doesn't have the scope, just click on the URLs below so you can look at a couple of samples on the internet:http://www.ebay.com/bhp/automotive-oscilloscopehttp://www.ebay.com/bhp/auto-oscilloscope Best Regards.
Customer: replied 1 year ago.
He does not have a scope. Is there an alternative procedure? I can't justify buying one of those units for something I might not use again :(
Expert:  Juan Crespo replied 1 year ago.
I'm afraid not. Even a voltmeter fast enough to read that signal would cost a heck of a lot more than a cheap scope. See sample here: http://www.amazon.com/Fluke-177-Digital-Multimeter-Backlight/dp/B00012Z0UW
Customer: replied 1 year ago.
I can borrow one of those from about 4 friends that do electrical work!
Expert:  Juan Crespo replied 1 year ago.
As long as your friends are automotive electricians. Meters made for AC won't read small DC signals. Make sure the one you borrow has MIN/MAX and AVERAGE capabilities.
Customer: replied 1 year ago.
Ok, get back to you tomorrow.
Expert:  Juan Crespo replied 1 year ago.
Will be here after 2PM ET.In the mean time, here is some interesting material:http://www.facstaff.bucknell.edu/mastascu/elessonshtml/Measurements/Scope1.htm Best Regards.
Customer: replied 1 year ago.
Just got home, haven't had time to get into the testing. But I did pop on a test light I rented. Here's a video of the results.
https://youtu.be/rw7iuQvAfbM
Expert:  Juan Crespo replied 1 year ago.
Thank you gor that video. It looks like the NE signal is initially there. What did the fuel pressure tester show? Did you remove the injector rail and powered up each injector individually?
Customer: replied 1 year ago.
That test light was on injector 4. Shouldn't the light be on when the key is switched to on before start? Or did that look like proper injector signal?
I just got a fluke meter from a friend. It has the functions you told me I needed. I plan on testing all of the items you list tomorrow.
Expert:  Juan Crespo replied 1 year ago.
Injectors 1, 2, 3 and 4 should only be on (Noid light flashing) when the engine is turning, otherwise the cylinders would flood. As I indicated after watching your video, the NE signal seems to be there initially, so testing with the voltmeter at this time wouldn't reveal anything new. Instead, focus on fuel pressure and individual injector operation. FYI, fuel pressure should be about 40 psi with ignition on. If you clamp shut the fuel return line and crank the engine, fuel pressure should rise to over 50 psi.Please let me know what you find. Best Regards.
Expert:  Juan Crespo replied 1 year ago.
Haven't heard from you in a while. How are you doing with that 4Runner?
Customer: replied 1 year ago.
I picked up a little work wed/thurs will be disassembling the efi tomorrow to test!
Expert:  Juan Crespo replied 1 year ago.
Looking forward to your findings. Best Regards
Customer: replied 1 year ago.
Damn, me too!
Expert:  Juan Crespo replied 1 year ago.
Cool. Let me know.
Customer: replied 1 year ago.
In the fsm, the procedure for testing fuel pressure illustrates testing at the fuel rail. The kit I rented does not have the proper fitting for that (round bit that the banjo would thread through, also the banjo bolt attachment was too long to thread all the way into the fuel rail) and had to be tested at the cold start injector with a banjo bolt fitting.
I followed the procedure otherwise, testing from the CSI. The gauge didn't bump a bit with fuel pump jumpered in diagnostic box or cranking ignition. Is something wrong with my test/gauge? Cause when I loosen the banjo bolt, gas sprays out everytime.
Should I test before the fuel filter?
Customer: replied 1 year ago.
Figured it out. There was a little piece that fell out of the valve that pushes down the nipple. 32psi
Expert:  Juan Crespo replied 1 year ago.
32 psi is on the low side of the specification. What was the pressure reading with the return line clamped off? Also, did you do anything with the injectors?
Customer: replied 1 year ago.
Zero change observed with return clamped.
Though, low, if you think it could run with that amount of pressure, I'm planning on replacing many things including the fuel tank/fuel pump once she's running and I know I'm not dumping money into a truck that I'm not going to be able to drive.
Expert:  Juan Crespo replied 1 year ago.
As I indicated previously: "FYI, fuel pressure should be about 40 psi with ignition on. If you clamp shut the fuel return line and crank the engine, fuel pressure should rise to over 50 psi".To clarify my position; all I can do from my end is guide you through the recommended diagnostic tests and procedures based on my technical knowledge and experience as a Master Technician. Not being an appraiser who could determine your vehicle's market value, I cannot tell you in all honesty whether or not any repairs you do to it are going to be a good investment. Best Regards.
Customer: replied 1 year ago.
Excellent, sorry for asking. FYI, if we get through this, I'm going to significant increase the payout for this service. You have been a tremendous help, and I apologize for wasting your time asking stupid questions that test your patience.
How to proceed?
Expert:  Juan Crespo replied 1 year ago.
Sorry for the delay.
I don't quite understand what you mean when you ask "how to proceed"? You mean other than what I previously indicated?
Customer: replied 1 year ago.
While testing fuel pressure, the fuel pressure damper sprung a leak around the screw. Took the fuel rail apart. Hadn't checked injectors before. They were completely clogged. I've ordered new injectors and a fuel pressure damper. Standingby.
Expert:  Juan Crespo replied 1 year ago.
I'm sorry you had to find out that the injectors were clogged in such a way, but I'm glad that you finally checked them. Looking forward to hearing from you. Best Regards.

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