OK,

Just a little background: 1990 Bronco with 302 bought about 3 months ago. Did eng swap with a crate 351W, EFI. The 351W runs great and I have a noticable increase in HP. But I have some problems that I just cant figure out:

The eng will sputter or misfire above 2500 RPM, not before - only after 2500. It seams to do it more after the eng warms up. I am not sure what it is, but I have checked everything (vacuum lines, distributor, timing, wires, plugs, electrical connections ect..) and no luck finding the cause.

The OD transmission will also shift into OD at somewhat slow speeds (35mph) and stay there. When I apply gas, instead of downshifting - it stays in 5th gear and sputters and cloggs. I have to give it at least half throttle to get it to downshift. It didn't do this before with the 302.

Also, after the eng warms up, sometimes the RPM's will surge from 600 - 1000 RPM, I have to put in neutral and give a littel juice to make it stop. It doesn't do this all the time, but sporatically.

All these problems feal "electronic" in nature, not mechanical (if that makes any since). The ECM is from the old 302 and I am thinking about swaping that out to see if it can hopefully fix some of these problems. Also the ignition coil is from the 302.

Anyone have any other ideas .

 

I'll give this a try. Others will too I'm sure. The sputtering/backfire above 2500 could be timing or more specifically the ignition module. If the distributor isn't advancing the spark correctly I can imagine this happening. The tranny not shifting sounds like what I had going for awhile. Is it adj'd right? There's the linkage attached to the throttle body right next to the accel. cable. Theres a tab that pulls up and adjusts the tranny shift in relation to the throttle position. (At least that's my understanding of what's going on)Mine also shifts into OD right around 35 mph but doesn't struggle or resist downshifting. The idle surge is discussed here alot. MAP sensor, TPS, IAC, all sorts of answers there. Then again, I could be way off. Just trying to help.

 

A 302 and a 351 have diffrent firing orders!!! Unless the 302 was a H.O. Swap the E.C.M. That should of been done with the motor change out. It could be pulsing the injectors at the wrong times,
Al

 

I should have mentioned that the 5.8 runs great on the 5.0 computer for about 20 minutes. After the engine heats up and runs for a while it starts to miss and backfire.

I hooked up the code reader and got a code 44 (thermacator air system inoperative - right side)??? OK so I changed my Air Charge Temperature sensor and still get the code 44.

Anyone have an idea what else this could be????

 

you need an ECM that is made for a 351w... no way around that. you can probably find one at a junkyard, or just order one from any number of websites. that ECM controls everything from spark and fuel to shiftpoints. It may be expecting a signal from that air charge temp sensor which is inconsistent from the 302 to the 351. the new ECM should read all the sensors properly, and will most likely fix the problems you are having.

-Josh

 

djjoshuad - Thanks for the input. I have tried and tried to get this worked out and it just wont happen

When I look back on all of this, the ECM must be the cause - its the only thing I haven't replaced!

Also, I "lost" most of my CA emissions stuff during the swap, (no more air pump, and air by pass valve, ect...) and the ECM is a CA ECM, soooo it is probably a little confused right now - not to mention the whole different eng thing.

I was looking for advice on this b4 I started this eng swap and the ECM change was a 50/50 shot - some said it worked fine - others said it would not work.

Chalk one up to experience

All - Thanks for the input

 

re:Also, I "lost" most of my CA emissions stuff during the swap, (no more air pump, and air by pass valve, ect...) and the ECM is a CA ECM, soooo it is probably a little confused right now - not to mention the whole different eng thing.
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this is exactly wy you are getting code 44....if you ever take it to an emissions inspection you wiill fail the emissions test on visual...missing emissions equipment...AND the code 44....and you will most likley have to go to a referee (don't go there) or a certified smog repair station....

I would plan on reinstalling that stuff...the air pump takes up about 1/3 hp. Lol....so no big gains there.

 

Just as a side note to ALSAIR, the truck fuel injection will happily run a 302 on standard or HO firing order. The bank fire arrangement distributes plenty of fuel in the right place for the system to work. Unfortunately, I don't know how to tell it to breathe for a 351.....

 

re:sputter...

it almost sounds like you are starving the engine for fuel...

pull some plugs and check the color and consistency....if white...=lean.

if yellow to brownish ashy deposit then normal...

if black soot or oily then rich and or worn rings, valve guides etc)

The 5.8 ECU should regulate the injector pulse width to run in conjunction with the larger displacement. I would get a 5.8 harness and transplant the 5.8 ECU....

If you want the best upgrade go with the MAF conversion...if yours is a manual AOD..then use the MAF conversion for a manual transmission.

 

I did this swap about a year ago. i used the 302 harness but a 351 ecu from fordfuelinjection.com . Ryan sold it to me for a very good price and has plenty. you might also replace your coil to and msd coil to. .

late

 

Thanks Kemicalburns,
You answered my next question (where to get an ECU). I'll give them a call. Once my wallet recovers from this eng swap, I will probably do some more upgrades (ignition, distributor, ect.)

Thanks for the info

later

 

i dont know how much it will be for a ecm on his truck, but autozone has the eec-iv for about a bill, try there. you can look online to save yourself a trip.

 

A little note on the sputtering when going over 2500 rpm's while under load. I too have a 90' with the 5.8L (351W) fuel injected engine, and had the very same problem that started about a year ago. Replaced fuel pump then ignition module on distributor, and then a whole bunch of other parts to try to solve this problem. Well come to find out 2 weeks ago that the ignition module was the wrong one. The first module I put on was apperantly for the carburator version of the 351w. So I swaped it out for the correct module, for the EFI, and that solved the problem.
The moral of the story = check the ignition module on the distributor. Make sure you have the one for the EFI, not the Carb.

What tranny do you have? The AOD, the AODE, or the E4OD? The linkage may need to be adjusted, if it's the AOD. The other two are electronicly controlled by the computer. Then like a few people have suggested, replace the computer.

This could be an air leak some where: gaskets to check = lower intake, or the lower intake to upper plinum, or the throttle body and/or the valve cover. Especially if it is consistant. But then again this could be related to the ignition module, Like above.

Hope this helps

 

tite4x4:

Thanks for the info: The tranny is the "E" and it is controlled by the ECU. I figured out that problem - the red/black vacuum lines from the control module to the canister on the passenger side were burned by the EGR pipe - thus not providing the right pressure to the module that controls the shifting. Since I repaired, the tranny is all good.

I have checked and re-check all vacuum lines and intake gaskets and bolts for proper fit and torque. It all checks out and it has since stopped sputtering, it is more of an backfire/mis-fire that occurs. I have stopped driving it because I do not want to damage the new eng. Also - paying over $2 a gallon and getting 8 mpg is killin my funds

I am waiting for new ECU for the 351w and upgrading the ignition. It really feels like the eng just isn't getting enough spark. I was also thinking back to when I had the 302 - the eng RPM fluctuated and surged with that eng too! Talking to local mechanic he suggested that the ecm was bad and it was a common problem with "CA Emissions" 1990's Bronco's. He showed me a tech report from Ford that talked about the RPM surge problem and how to test if the ecm needed replacing. It explained exactly what is happening - RPM surge of 100-300 RPM during idle and not present above 1500 RPM. Only way to fix is replace with the "Fed" ECM.

Thanks for all the suggestions - I really hope the ecm and ignition fixes the problem. After all - this is getting to an expensive project

 

let us know when you get this replaced