Fuel Injector Tester build

Brownout

Joined Jan 10, 2012
2,390
Ok then what would you suggest..
Gonna put me on the spot, eh? Well, first you would need a profile of the injector, time to fully open, time to fully close, volume, etc. I'm not an expert here, but I do know that injectors work at alot higher frequency. What I'm saying is, you need to design your tester to the injector specs.

Again, not an expert, but I think injectors would need to be driven hard and fast. And so, pay particular attention to the gate drive of your pass device. You'll need a minimum drive, based on gate capacitance and minimum turn on time. Someone earlier mentioned a driver, maybe it's worth taking a look at. Bottom line, after you have all the requirements for testing the specifications for your injector, then we can begin to design a circuit for it.
 

blocco a spirale

Joined Jun 18, 2008
1,546
All the necessary information for driving injectors, building an injector tester and testing the injectors is available in the link from post#12; so why are these same questions being repeated 9 posts later?

As with many threads here, the TS is ignoring all the information and advice provided.
 

Thread Starter

Dr.killjoy

Joined Apr 28, 2013
1,196
I take the TS is using this circuit as a basic test jig.

As a test jig, it will perform a functional test on the injector, whether it opens and closes properly, and allow the mechanic to see if there is flow or not flow .... and possibly the cleaning that was mentioned.

Improvements to the circuit would require a definitive listing of what one requires of their injector tester.
I plan on using the circuit as you listed and I looking if there should be improvements

You may be interested in this. It was designed by the guys that make the Mega Squirt ECU.

http://www.bgsoflex.com/fitester.html
Thanks for the information here but I don't have a programer and that's alot of options just for a simple test and it's not like I was Dyno a motor or building a race car..



Can't imagine how you will do that with the injector installed in the vehicle? With an injector installed all that is visible is the wiring connector, how will you tell what is going on with the spray nozzle that is down inside the intake manifold? When testing an injector, they usually spray into a beaker or other container and measure the amount and spray pattern for a given time. To check in the engine if it is even working you just need to unplug and see if that cylinder stops firing no 'tester' needed.
Still don't see how that would really tell you anything about the injector. A mechanics stethoscope on the injector body with the engine idling would do the same thing.
Apart from pulling an injector out to see the spray pattern, ive just unplugged each injector plug until the faulty one is found. Usualy find that the faulty one is blocked. Some ive recovered by removing the internal filter basket & reverse flush.
I'm with shortbus on this one. Really sounds like you're making a big job out of this when it's really as simple as pulling a spark plug wire on a 1965 mustang. Unplug wire, no difference, bingo. That's the bad one.

The last one I did (2008 Chevy Van) was ratted out by the on-board computer. Look ma! No brains required!
With the stethoscope all your are hearing is the solenoid valve opening and closes ..With the tester I can save time without going through with removing the injectors and removing the connector to find the bad one will help if the injector is bad but will not help with a random missfire or the injector is not sealing .. With this I can test each injector wither it is holding pressure or the connector or harness is the problem .. Also I can do a basic flow test inside to see any other issues .. For me to pull the injectors to bench test them is a waste of time IMO unless you are building some kind of race motor.. Cause then you have to replace all the o-ring and gaskets and a whole alot of work for 1 injector and later down the road you might have to replace another injector. In that case I would just get brand new injectors from RockAuto and be done with it ..
I was thinking about using the tester with a fuel rail cleaning to help clean out old injectors too..


Gonna put me on the spot, eh? Well, first you would need a profile of the injector, time to fully open, time to fully close, volume, etc. I'm not an expert here, but I do know that injectors work at alot higher frequency. What I'm saying is, you need to design your tester to the injector specs.

Again, not an expert, but I think injectors would need to be driven hard and fast. And so, pay particular attention to the gate drive of your pass device. You'll need a minimum drive, based on gate capacitance and minimum turn on time. Someone earlier mentioned a driver, maybe it's worth taking a look at. Bottom line, after you have all the requirements for testing the specifications for your injector, then we can begin to design a circuit for it.
Sorry for putting you on the spot there...My plan was to use it to test all kind of injectors since I work on all different cars..

All the necessary information for driving injectors, building an injector tester and testing the injectors is available in the link from post#12; so why are these same questions being repeated 9 posts later?

As with many threads here, the TS is ignoring all the information and advice provided.
I asked cause he brought up a different point and yes post #12 does answer the questions but I was asking his opinion and plus I don't have the tools right now to build the circuit in post#12 ...I am not ignoring anything and stated above I was looking to build both circuit stated in the OP and by Shortbus and see what works best or I like better .. I do understand about people ignoring the information giving or just plainly looking for someone to do the work for them ..
I do apologize for any misunderstanding ..
Jay Sr
 

Thread Starter

Dr.killjoy

Joined Apr 28, 2013
1,196
BTW, after you test the injector in the engine, what happens to all that extra fuel that ends up in the cylinder?
Good question ..
Your suppose to remove the spark plugs not to hydro lock the motor and you can turn the engine a couple times to expel the extra fuel out the plug holes..
 

blocco a spirale

Joined Jun 18, 2008
1,546
I wasn't suggesting building exactly the circuit in the Post#12 link.

The output stage (in the linked article) provides the correct drive for the injector by using a dedicated IC to control the current, although you may choose to drive the output stage differently. Your original circuit does not provide the staged current control and this will affect the performance of the injector.

There is also some useful information regarding testing methodology in the article. I agree with the opinion expressed by others that trying to test the injector on the car (using an injector tester) is pointless as it only tells you whether fuel is being introduced or not and this would be obvious when the engine is running.
 

PackratKing

Joined Jul 13, 2008
847
I have found, that if an injector can be cleaned, does not leak under pressure, delivers and will demonstrate a uniform spray patternwhen held open for a second, and instantly shut off cold... they will continue to deliver millisecond pulses...
 

shortbus

Joined Sep 30, 2009
10,045
With the stethoscope all your are hearing is the solenoid valve opening and closes ..With the tester I can save time without going through with removing the injectors and removing the connector to find the bad one will help if the injector is bad but will not help with a random missfire or the injector is not sealing .. With this I can test each injector wither it is holding pressure or the connector or harness is the problem .. Also I can do a basic flow test inside to see any other issues .. For me to pull the injectors to bench test them is a waste of time IMO unless you are building some kind of race motor.. Cause then you have to replace all the o-ring and gaskets and a whole alot of work for 1 injector and later down the road you might have to replace another injector. In that case I would just get brand new injectors from RockAuto and be done with it ..
I was thinking about using the tester with a fuel rail cleaning to help clean out old injectors too..
Jay Sr
Again without having the injector out of the engine, what are you going to see? Or what will pulsing it tell you? And what is it going to tell you more than the stethoscope? Uncliping a connector takes the same amount of time to test function as it does to put on a 'tester', and will tell you much more.

As far as the O rings go, I've never replaced the rings unless they came with a gasket set. They don't stick or break when removing a fuel rail and there isn't enough pressure on them to distort them so just reuse them.
 

JoeJester

Joined Apr 26, 2005
4,390
I plan on using the circuit as you listed and I looking if there should be improvements
That would depend if you are satisfied with what that tester currently does. What do you want the tester to do?
 

JoeJester

Joined Apr 26, 2005
4,390
Right now you have the choice of a 1 second 3600 RPM test or a 5 second 3600 RPM test for the injectors. I realize it's actually approximately 3573 RPM. What you want it to do will determine the modifications and improvements required.

Bench testing the injectors would have a different set of specifications.
 
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