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I was reading a post the last week or so and there was a discussion about the best injectors for the 4.0L Renix, and the consensus was that the Bosch 9454555 injectors were the best.

These injectors came on late 90's model Volvo Cars and were Volvo Part #0-280-155-746.

 

I have been have problems with engine performance on my 88 model Comanche Chief, so I thought I'd give it a shot.

Hard Start, stumbling on acceleration, lack of power that I know these engine have.

 

I bought 6 used Bosch injectors on E-*** for $36 delivered.

I cleaned them and flushed them out with fuel injector cleaner.

I did this by making a electrical plug for the injectors and attaching it to a 12V battery....., (2) Stacon mini-spad female connectors, 3 inches of 1/8" shrink tubing and 6' of small gage 2 conductor electrical wire (I used speaker wire). 

Mark the positive lead at both ends

 

I then energized (12V) the injectors (hooked it up to a battery) up) one at a time to open it and shot a short burst on cleaner thru the injectors. 

I got a good atomization of the cleaner and all four ports of the injectors were spraying a good pattern. 

There is a (marked) positive and negative terminal on these injectors, so don't hook them up backwards when cleaning/testing.

Also, don't leave the injector plugged up for too long when holding it open, you could damage it.....I did about 15 seconds per injector.

 

I then installed the injectors, it took me about 1 hour.

They are a true "plug and play" swap with no modification to the fuel rail required.

That included cleaning the injector ports in the intake and putting on new O-rings (I had them from a long time ago).

Be sure to loosen the mounting for the solid return fuel line that comes off the fuel pressure regulator.

That will allow you to slide the connector straight out as you mash in the tabs on the quick connector.

I unplugged both connectors without any damage.

You're supposed to replace these connectors every time you open them but I don't see any reason if they don't leak.

 

I must say that I was pleasantly suprised at the change of performance of the 4.0L engine.

Smooth idle, no more "dead spots" on acceleration and much more power.

I sure that my fuel economy will increase, but I haven't checked it yet.

 

When I first started the engine after swapping the injectors, the engine would barely idle and blew a lot of white/blue smoke when revving.

OH S***!

 

I went back over my installation to make sure that I hadn't missed something, and finally found that I had un-plugged the 1/8" vacuum hose from the intake to the MAP Sensor.

I didn't realize how much affect that little sensor has on engine performance.

I plugged the hose back up and the engine settled down immediately.

It's never run better since I've owned it and that's about 18 years.

 

Oh yea, I also pulled that battery cables and held the positive and negative cable together for about 15 seconds to reset the Renix computer.

It must have worked because the engine is nice and smooth.

 

steve

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I don't think the Renix computer retains any memory what-so-ever. So, I don't think that did anything. The MAP sensor will cause the car to not run, or run poorly if there is any vacuum leak at all. 

 

I have a HO swap, and put the Neon injectors in. They made alot of difference in idle/throttle response. Not much in fuel economy. Easily worth the upgrade though!

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  • 6 years later...

I am very sorry to revive a very very very very very very very very very dead thread, I just wanted to see if everyone thinks these injectors are the best for my Renix 4.0 or if there is a better alternative.

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Probably would have been just as informative to start a new thread and get comments from people who have done this in the last couple of years. Not bashing you at all, just a suggestion. That said, Bosch 746 injectors IMO seem to be the most widely used injector upgrade on the Renix 4.0 and I have yet to read a negative comment across many forums. Affordable, readily available, properly spec'd for flow rate etc.........best upgrade I've done. Instant improvement in smoothness of idle and acceleration. I believe I gained some mpg but I have not measured it in great detail, just getting more miles per tank. :L:

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2 minutes ago, MiNi Beast said:

be a good swap for you. in simular boat myself. we can benefit with the 4 hole injector.  

Thanks!

 

2 minutes ago, WahooSteeler said:

Probably would have been just as informative to start a new thread and get comments from people who have done this in the last couple of years. Not bashing you at all, just a suggestion. That said, Bosch 746 injectors IMO seem to be the most widely used injector upgrade on the Renix 4.0 and I have yet to read a negative comment across many forums. Affordable, readily available, properly spec'd for flow rate etc.........best upgrade I've done. Instant improvement in smoothness of idle and acceleration. I believe I gained some mpg but I have not measured it in great detail, just getting more miles per tank. :L:

Thank you! I thought about creating a new thread. Actually, I had started one, but I wanted to start with a good base that already had some info.

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Did this swap a couple of years ago.  Noticeable improvement in idle and smoother and better acceleration.  Nothing mind boggling but noticeable.  Can't speak to mileage as I didn't do a before and after.

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2 minutes ago, rokinn said:

Did this swap a couple of years ago.  Noticeable improvement in idle and smoother and better acceleration.  Nothing mind boggling but noticeable.  Can't speak to mileage as I didn't do a before and after.

I'm not really worried about my mileage, but my injectors in both of my engines aren't much good anymore. Do you remember which ones that you went with?

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3 minutes ago, 89 MJ said:

I'm not really worried about my mileage, but my injectors in both of my engines aren't much good anymore. Do you remember which ones that you went with?

Are you asking which injectors or where I got them.  In either case I'll have to dig a little to see if I can be more specific.

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1 minute ago, rokinn said:

Are you asking which injectors or where I got them.  In either case I'll have to dig a little to see if I can be more specific.

Which injectors. If you don't remember, I am not worried about it. You don't need to go digging for me.

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21 minutes ago, 89 MJ said:

Which injectors. If you don't remember, I am not worried about it. You don't need to go digging for me.

Found it!  I did the Volvo injectors.  I think that's got a 746 on the end but don't quote me.

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No problemo.  Gotta do something with this day and I can't go outside, smokes too thick.  I'm not too far from the now largest wildfire in CO history.  Cameron Peak.  Gotta wear my P100 mask just to go outside.  Nasty.

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2 minutes ago, rokinn said:

No problemo.  Gotta do something with this day and I can't go outside, smokes too thick.  I'm not too far from the now largest wildfire in CO history.  Cameron Peak.  Gotta wear my P100 mask just to go outside.  Nasty.

Geez. The west just can't catch a break with these fires. Stay safe!

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The key to getting a set is to make sure the seller has not just cleaned them up with new orings and filters, but has tested and flow-matched them for consistent pressure across all 6 injectors. There is a guy on either NAXJA or CherokeeForum that has been rebuilding them for years, Cruiser knows the guy I believe and can refer you to him but not sure if he is still doing them. Otherwise I would recommend ebay so you can see better feedback and a more detailed description to make sure they are flow matched. For me, Amazon doesn't give me as much confidence as ebay on things like this. Another option that will cost you a bit more but you're getting a known product with proper rebuild and flow matched is KSuspension. I've heard they are good to deal with and very fair if you have any problems also. 

 

https://www.ksuspensionfab.com/store/p8/Remanufactured%3A_4_Port_Upgraded_Fuel_Injectors_XJ%2FMJ.html#/

 

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1 hour ago, WahooSteeler said:

The key to getting a set is to make sure the seller has not just cleaned them up with new orings and filters, but has tested and flow-matched them for consistent pressure across all 6 injectors. There is a guy on either NAXJA or CherokeeForum that has been rebuilding them for years, Cruiser knows the guy I believe and can refer you to him but not sure if he is still doing them. Otherwise I would recommend ebay so you can see better feedback and a more detailed description to make sure they are flow matched. For me, Amazon doesn't give me as much confidence as ebay on things like this. Another option that will cost you a bit more but you're getting a known product with proper rebuild and flow matched is KSuspension. I've heard they are good/fair to deal with if you have any problems also. 

 

https://www.ksuspensionfab.com/store/p8/Remanufactured%3A_4_Port_Upgraded_Fuel_Injectors_XJ%2FMJ.html#/

 

Thank you!

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