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Renix injector swap issues

etaoin2

NAXJA Forum User
Well, I've been lurking and searching for over a week now taking in as much information as I can, and I'm still having problems, so I thought I'd suck it up and post my very own thread.

To start, I drive a 1987 Wagoneer with the Renix 4.0l. (AW4/NP242/D30F-D44R, don't think that's relevant but more info never hurt, eh?)

I started smelling gas in the cab, so I went to take a look and lo and behold, a few of the injectors were definitely leaking where the metal and plastic meet on the injector. I got a set of Ford 19# injectors, as I'd read on here that they're a pretty popular swap.

Problem is, now I have to give it almost full throttle to get it started, and it blows some white smoke for a little while until it warms up. It smells like it is running rich, but I don't see black smoke. When I'm driving above ~30mph and I give it just enough throttle to hold speed, it shakes alot. It idles alright, but shakes more than it used to, if i give some throttle it smooths out with higher RPM. If I give it alot of throttle and then let off quick it either dies, or almost does and then picks back up.

Fuel pressure at the rail checks out like it should, cap/rotor/plugs and wires are all new, along with 02 sensor and MAP. I reset the PCM by disconnecting the battery for a while, and then key on-headlights on-headlights off- key off. I read that it gathers data for 50 start up cycles.

Should I just drive it for a while and see if it evens itself out as the PCM gathers data? Can you guys think of anything obvious I may be missing? I'd like to apologize in advance if the answer is on this forum and I'm just an idiot, but I've been searching NAXJA and the whole internets for a while and I'm not getting it.:dunno::confused:
 
If the injectors were used and have sat for a while, put a can of BG44K in the fuel.
 
First off, I'd like to say thank you for the quick reply.

I got the injectors from Precision fuel injectors, and installed them the day after I received them. They were in the bag until I did the swap.

I also just listened to the injectors through a screwdriver and verified that they were all pulsing.

I didn't mention before, but as to be expected with an engine not running properly, power and MPG are lacking.
 
Check and see if you knocked the vacuum line from the throttle body to the MAP sensor loose when working on the injector swap--could have come loose on either end.
 
Check and see if you knocked the vacuum line from the throttle body to the MAP sensor loose when working on the injector swap--could have come loose on either end.
It is sometimes a poor fit where it goes into the throttle body, old rubber dries up and shrinks, old plastic lines crack too
 
MAP sensor was my first thought, but I checked that and went on to check all the vacuum lines. Had to replace the CCV hoses as the rear was clogged and the front was cracked and chewed up, but aside from that it was all in working order.
 
Ok. How about a damaged o-ring? Pull the rail loose enough to free each of the injectors, pull them one at a time and inspect the o-rings. Did you lubricate the o-rings before installing--Petroleum Jelly is a mechanics best friend. You can also use a .410 shotgun cleaning brush to clean the openings in the intake manifold and fuel rail.

If that doesn't do it, then pull one spark plug wire at a time with the engine running to try and I.D. the problem cylinder.

EDIT: one last thing, did you check the vacuum line to the FPR? I doubt it would give you the full range of symptoms, but worth a look anyway.
 
I did use petroleum jelly during the install, everything seemed to go in smoothly. Maybe I just didn't press them in hard enough to get a good seat before I bolted in the fuel rail, I will check that tomorrow when there is light. While cleaning the intake manifold openings, should I be worried about stuff I brush off falling in? I get paranoid about cleaning stuff when gravity wants to pull debris into the engine. The FPR vacuum line is fine.


Thank you all for your input, it is very much appreciated.
 
I wouldn't get too concerned with a little crud getting into the intake, fuel rail side shouldn't be any problem at all.
 
I'd make sure I had vacuum at the MAP sensor. Your symptoms are pointing to a MAP issue as Joe initially said. Could be a clogged line, cracked line, melted shut line, poorly seated line in TB.... to the MAP.Double check everything you touched during the injector installation.
 
Map sensor
Fuel Pressure Regulator (needs vacuum) if the FPR is not getting vacuum it will keep the fuel pressure too high, especially for idle/part throttle situations.

The Renix ECU will not "relearn" anything, ever. It does not have a storage medium, and is completely adaptive to the motor in real time. Damned amazing piece of hardware for 20 years ago.
 
I checked all of the vacuum lines multiple times and they all checked out good.

So I pulled the new injectors and put the old ones back on. It fired right up and runs great. I guess I must have gotten a bad set or something, unless there is something that needs to be done to make the Ford 19#s function properly, but from what I hear they are a direct swap.

Has anyone else had experience with Precision Auto Injectors? I guess I'm about to find out how good their customer service is...

Funny thing is, when I pulled the old injectors a couple of them were leaking horribly, now they seem to be functioning just fine. I still plan on getting new ones, but I thought that was weird.

Thanks for the info on how the Renix ECU functions, that's pretty neat for such an old system, I'm still learning how some of this stuff works.
 
http://www.veryuseful.com/mustang/tech/engine/images/Ford_Injector_Guide.jpg

Orange top/Silver body, Orange top/black body, Yellow top/black body--these would all be Fat Boys. The later "Stick" injectors are all one color.

You want the disc type injectors with 4-hole nozzles, not the single pintle design.

Note that the green stick in the row of 19 lb injectors in the photo has the later EV6 style connector.

You could re-install the Ford injectors you have from Precision ONE at a time, test it. That way you could ID the bad one(s).
 
I'm not planning on driving it or having it running with the old injectors. Just threw them on to see if it was the new injectors that are malfunctioning. I could tell as soon as I started it up.

They are yellow top 19# injectors, fat body style not stick, with the four holes. They look like the stock Mustang 19# on the link but with a silver body. The place I bought them from says they are compatible with the Renix 4.0l. Everything went in smoothly, and there's no leaks, but they cause the engine to run like crap.
 
Same thing I'm running. I would definitely try installing one at a time and try to isolate the bad one.
 
I'm getting in contact with the company I bought them from to get it sorted out, I'm not sure if they'll want the whole set sent back or what. If I do need to find out which one is defective, I'll test them out like you suggested.
 
Thinking I might not have been clear. Swap say no. 6 and start it--runs good then swap number 5, and so on. You might end up with 5 good ones and use the best old one until the replacement arrives.

Good luck.
 
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