Ford guys let me know what you think. TIA

[OVERKILL]

Originally Posted By: ADFD1
I'm wondering myself if bad base timing could cause a surge? My toughts are probably not. Pinging, and lack of power but not a surge.


Correct. I've never had bad timing cause the surge.

 

[ADFD1]

Originally Posted By: OVERK1LL
Originally Posted By: ADFD1
I'm wondering myself if bad base timing could cause a surge? My toughts are probably not. Pinging, and lack of power but not a surge.


Correct. I've never had bad timing cause the surge.


Just wondering. Can a base idle higher than normal cause a surge?

 

[OVERKILL]

Originally Posted By: ADFD1
Originally Posted By: OVERK1LL
Originally Posted By: ADFD1
I'm wondering myself if bad base timing could cause a surge? My toughts are probably not. Pinging, and lack of power but not a surge.


Correct. I've never had bad timing cause the surge.


Just wondering. Can a base idle higher than normal cause a surge?


I'm not sure. I've used a base idle higher than normal to FIX the surge though.

 

[ADFD1]

How much higher than normal?

 

[OVERKILL]

Originally Posted By: ADFD1
How much higher than normal?


600-700RPM usually puts the idle around 900. This was for a cammed Mustang though.

 

[demarpaint]

I found the directions for the spacer plate Ford sold for under the IAC. In those directions is said something like trying to set the base idle as low as possible to avoid a surge. I'm thinking of checking timing, just to be sure it is in spec, and lower the base idle to the lower limit of the range they give. If that doesn't work I can change it to the higher end.

 

[OVERKILL]

Yup, if you can get her to idle at 450, set it there. As I said, the INCREASE was necessary for a FAR from stock engine. So I wouldn't necessarily immediately apply that logic to your scenario.

 

[demarpaint]

Thanks for all the help. I was willing to try both extremes, but I've already been toward the high end of the range, so trying the lower might help. While I'm in there I will see if I can get a picture of that vacuum hose that goes nowhere and post a picture of it. I'll also test around the injectors again for vacuum leaks.

 

[demarpaint]

Well here's an update. I had some time to fool with the spacer plate below the IAC. I disconnected electric to the IAC, and had turned both allen screws all the way in allowing no air. The engine would not run [exactly as I expected]. I opened one screw until it would start and idle, it was rough and surging up and down. I tweaked it by opening up the screw until I had the best possible idle around 525-550 rpm, which is in the range of what the base idle should be. I reconnected the IAC and it idles nice and smooth. After about 15 minutes shut down peroid when I restart it, it will surge about 2 times and then level off. Before it would surge until I hit the gas pedal.

At this point I'm going to have to live with it, since that is the best I can get it. I checked again for anything that might be loose, and for vacuum leaks. Found nothing, again.

I have a spare TPS should I toss it on for S&G? Which means re-learning idle strategy, a PIA for the first 100 miles. Or do I leave well enought alone and be happy a 21+ year old van is still looking and running as good as this one? I've tried different TPS and IAC with no luck in the past.

Thanks!

Frank D

 

[ADFD1]

Still at it? LOL...........Sounds like you are making some progress. 20 something Y/O vehicle, it might be running as good as it will run.

jmo

 

[demarpaint]

Yea still at it. I'm about 85%, still has a little surge on the engine warm restart, and on a cold start it needs to run a little before taking off, other than that its OK. When I have the time and am into it I'll spend more time with it. The truck looks awesome, and I want it to run like new, OCD I guess.

 

[ADFD1]

I know you want 99%, have at it. I tossed in the towel on my buddies F-150 for now, it's running OK, not great. I'm keeping a watch on this thread since the issues are very similar. Good luck man!

 

[demarpaint]

I spoke with a mechanic buddy this morning and I am going to have him do another FI cleaning via the rail. They use a 3M product, disable the fuel pump and run it off an aerosol can. For $60 it is worth a shot, if that doesn't work I'll live with it.

 

[OVERKILL]

Never found a set of 4-holed injectors for it?

 

[demarpaint]

No, but then again I really haven't looked yet. I figured I'd have the injectors cleaned via the rail again. I was talking to my mechanic buddy this morning about it. He was one of the guys that spent some time with it. I asked him again if he checked for vacuum leaks and he said he used a smoke machine on it? It had no leaks, he guaranteed me it had none. I have no reason not to believe him. I tried carb cleaner, and propane another time and couldn't find any. If the injector cleaning doesn't work I'll check the junk yards and install them in the spring.

My mechanic buddy said if it was his van that had the surge on the warm engine restart and a touch of the gas resolved it he'd leave it alone. I will do that at least for the winter.

How difficult a job is it to replace the injectors on a 4.9L in a van?

 

[OVERKILL]

Shouldn't be too bad. You just pull the rail, and then you can pull them all out. If you lube the o-rings on the new ones well, they will go right in.

 

[demarpaint]

I'll have a look at the shop manual, and see what's what. Maybe the second cleaning of the injectors via the rail will do the trick. If not I'll have something else to do.

Thanks for the replies!

 

[ADFD1]

Second cleaning via the rail? Is that a good idea? My bet is u haven't even logged a 1000 miles since the last rail cleaning? Let me know how it works out for u?

 

[demarpaint]

Hey AD, Will do! The mechanic and I don't think it will be any issue at all. What sucks is I changed the oil about 100 miles ago, it was a year since the last OCI. The weather was good and I went for it! I might run a 6 month OCI this time though, I'll see how many miles I log by June. I'm going to fix this thing by hook or by crook!

Take care!

 

[demarpaint]

Well here's an update for those who were following this thread. I had the injectors cleaned again, and warm restarts have improved the surge isn't as bad. It might surge once or twice and quickly recover. I need to get it on a long run and beat on it a little. Now that it is very cold it does feel a little low on power until the engine starts to warm up a bit. I always noticed that though.