Rough idle when truck is cold

[Nilley]

Hi all, I bought a 01 f-150 7700 in Phoenix last dec and it has ran great for me until now. It has 68k on it; I bought it with 60k. It has a little trouble when I just start it up in the morning for about the first five min it will sometimes quit on me. Also last week I was pulling a boat up from sgu (6000k)aprox weight and it started surging a bit on the cng. Felt similar to when it switches over to reg gas.

Im guessing the injectors are dirty, any one else had this problem? How effective is running the 80% iso alcohol in the filter for 15min? I plan on changing the filter as soon as I can get one, (any one who has some please pm me) and trying the alcohol. Also what plugs do you recommend?

Thanks Ben

[rothstar]

Re: Rough idle when truck is cold

See my F-150 Buck/Jerk post. http://www.cngchat.com/forum/showthread.php?t=1321
Also, the Ford TSB mentions that the alcohol should be at least 90% isopropyl. You can get 91% at Walgreens for a couple of bucks.

[darress]

Re: Rough idle when truck is cold

Hi. My 2001 f150 7700 with 126k miles had this same problem. I tried the cng flush and filter change but it had no effect on the rough start and idle when on cng. I did the tune up with Bosch platinum iridium fusion (4 prong) #4505 plugs, Accel super coils #140032, and viton o-rings from Sno-Motion. The truck is running great after the tune up with a smooth idle on cng. I would imagine your original parts are still in place and the factory o-rings on the cng injectors dry out, shrink, and may crack. This seems to create the rough idle from most of what I have seen. The systems do get dirty inside and the alcohol flush will help to keep the compuvalve and related cng hardware clean inside.

[Nilley]

Re: Rough idle when truck is cold

Hi. My 2001 f150 7700 with 126k miles had this same problem. I tried the cng flush and filter change but it had no effect on the rough start and idle when on cng. I did the tune up with Bosch platinum iridium fusion (4 prong) #4505 plugs, Accel super coils #140032, and viton o-rings from Sno-Motion. The truck is running great after the tune up with a smooth idle on cng. I would imagine your original parts are still in place and the factory o-rings on the cng injectors dry out, shrink, and may crack. This seems to create the rough idle from most of what I have seen. The systems do get dirty inside and the alcohol flush will help to keep the compuvalve and related cng hardware clean inside.

Thanks, I bought a filter from snow motion, it was worth the drive for 60 dollars in savings over champions filter price, I had Champion do the flush. They said they flushed it twice, and that my filter had failed. They guy I talked with Joe, I think it was showed me the filter they pulled(part of the paper looked like it had blown out), and said the cartridge was full of oil. He said the paper can get stuck in you injectors and clog up you compuvalve.
I have no problems now with the truck quitting on cold starts, but I get a hint of a surge when accelerating on the freeway. Could be the plugs. I have not pulled anything with it yet so that will be the true judge as to weather it truly solved the problem. Thanks for the info on plugs, that’s my next step.

I love this truck, I figure it would have cost me around 200 dollars to drive to Saint George and pick up a boat on regular gas; instead it cost me about 40 round trip.

[Nilley]

Re: Rough idle when truck is cold

Hi. My 2001 f150 7700 with 126k miles had this same problem. I tried the cng flush and filter change but it had no effect on the rough start and idle when on cng. I did the tune up with Bosch platinum iridium fusion (4 prong) #4505 plugs, Accel super coils #140032, and viton o-rings from Sno-Motion. The truck is running great after the tune up with a smooth idle on cng. I would imagine your original parts are still in place and the factory o-rings on the cng injectors dry out, shrink, and may crack. This seems to create the rough idle from most of what I have seen. The systems do get dirty inside and the alcohol flush will help to keep the compuvalve and related cng hardware clean inside.

I looking at picking up some pulstar plugs, but they are expensive 25 dollars each. So my question is should I opt for the accel super coils and a cheaper plug or the pulstar plugs and a average coil? Also how do you go about replacing the factory o-rings? Thanks for your help

[Nilley]

Re: Rough idle when truck is cold

Hi. My 2001 f150 7700 with 126k miles had this same problem. I tried the cng flush and filter change but it had no effect on the rough start and idle when on cng. I did the tune up with Bosch platinum iridium fusion (4 prong) #4505 plugs, Accel super coils #140032, and viton o-rings from Sno-Motion. The truck is running great after the tune up with a smooth idle on cng. I would imagine your original parts are still in place and the factory o-rings on the cng injectors dry out, shrink, and may crack. This seems to create the rough idle from most of what I have seen. The systems do get dirty inside and the alcohol flush will help to keep the compuvalve and related cng hardware clean inside.

Thanks for the info, I bought the accel super coils, they should arrive soon. I called snow-motion and asked them about replacing the plugs, coils, and o-rings,and they wanted 1,200 dollars. I guess I will do it myself. Jayson said that he would not put the accel super coils in, he would only install factory spec parts because it (accel coils) could mess with the computers. Have you had any problems with your new set up? I think I will still install the hp coils and take my chances.

[Nilley]

Re: Rough idle when truck is cold

Ok I finally finished with the coils, plugs, and o-rings. What a p.i.t.a! I put on the accel super coils, ngk iridium plugs, and vition o-rings and it runs great! Just took it up the canyon to Sundance for a lot of lugging on the engine, and no shutter/buck.

For all you do-it-your-self-ers here is what I learned that may help you out. First: this is a royal pain in the a$$!
I looked up changing ford 5.4 spark plugs on Google and got a lot of good info. Start with that. In addition to what you need to remove for a regular ford you will have to remove the compuvalve, it’s just easier to pull the main electrical attachment on the back of the housing (the one screwed in) than unsnap all the attachments. I unbolted the cng line off the back of the housing. The only other place I had to dissemble a cng line was on the left side cng fuel rail (to create room for the gas fuel rail to be lifted up and off).

I found my brass cng injectors were very dirty, and used some carb cleaner on them. (The cng injector is a brass or plastic type cup the gas injector sits in) There are three 0-rings on each cng injector that you replace. Pm me and I will get you the part number for each o-ring (brass injector only) if you are interested. Snow-motion wanted 80 dollars for the set, the Champion Ford 35, but lesser quality. I found them at a specialty store in slc for 10 bucks; I also got 2 spares of each o-ring. You will need some o-ring lube; I purchased parkers for about 10 dollars. When re-inserting the injectors snap them all in place first, then put in your coils, insert your gas injectors they should snap in (I found it best to use some grease and snap the gas injectors in the cng injectors a few times before putting them in the truck). Once you have your injectors and coils in place comes the tricky part. I found it worked best to snap the cng fuel lines in to the cng injectors next, then put the 7mm bolts on to tighten the coils, it takes a bit of shimming but you will get it. Once you have tightened all 7mm bolts you can snap the gas fuel lines on the top of the gas injectors.

Some tools that are necessary are u-joints and extension for your socket set and 11in needle nose pliers.

Also I gaped my plugs at 4.5, I read on another forum that folks were getting better fuel econ. with the smaller gap. I will let you know it this worked.

Hope this helps.

On a side note, I have drove this truck about 13k since I bought it. I figured that if I had burned reg gas @3.85 per gallon it would have cost me arround 3,000 dollars, on cng about 500. So it has saved me about 2500 dollars just gas in 6 months! Thats not counting my 2950 tax credit.

[damonlo]

Re: Rough idle when truck is cold

Great thread !! About how long did the whole proceedure take,(by yourself or with help), also where did you get the o-rings, cop, plugs and their brands and prices.

Thanks Damon

99 f150 bifuel 96k(not running on cng correctly yet
)

[Harpoon]

Re: Rough idle when truck is cold

Here is the price part list when I did my tune up. Sno-motion charges $1500 for this tune up. It took me ~8 hours to complete. Next time I am going to do one side each Saturday starting with driver side

Coil packs (~$100 ebay)
Plugs (~$25-$30 Checker/autozone NGK)
O-rings (~$80 from sno-motion now that I have the sizes I am headed to EVCO for my next set ~$10) You need to know if you have brass or plastic injector cups.

-Harp

[Nilley]

Re: Rough idle when truck is cold

What local supply store did you get the o-rings if you don't mind

I can’t remember off the top of my head, I’m in Chicago now, when I get home I will check out the receipt and get ya the part numbers and shop location and number.

[darress]

Re: Rough idle when truck is cold

Nice post on your work. I have about 2 months since my tune up and still running strong.

A company called HydraPak Seals in SLC (801-973-7325) has the viton o-rings but I didn't get the measurements (stupid, I know). I found that the kit from sno-motion had a "standard" size o-ring for the very bottom of the injector assembly so I opted to get the "metric" size for a better fit. That particular one is part number 011.00x2.00v75. I will try to post a couple pics of the set and close up of the one I felt was undersized in the kit.

I have the plastic "pipes" on my system. The close up of the two pipes end-to-end shows the two different o-rings. The black one is the metric o-ring I used. Viton can be other colors besides brown, they said that was just for sight identification.

[Nilley]

Re: Rough idle when truck is cold

thank you have a good time

Sorry, it took me so long to get back; we had a medical emergency out of lax, and had to return to the field Friday night/morning. I did not get home until 5 am sat.

Hydrapak seals Inc, 3782 w. 2340 s. suite e slc Utah (800) 669-9638

The o-rings are for the brass injectors.
Small ring part # 2-106v75br
Medium part #2-013v75br
Large part #2-119v75br

Hope this helps. As far as the gaps on the plugs go increasing fuel econ, it’s too early to tell yet but looks like my econ has improved. Also the truck is running great, with more power, and no buck or surge!

[Airliner]

Re: Rough idle when truck is cold

I am in total awe of all your expertise in doing this stuff yourself. My 99 F250 bi-fuel has a rough idle after replacing the compuvalve and Champion Ford wants $1100-$1200 for the tuneup. Any chance any of you with mechanical experience want to help? I have a pair of airline tickets to the east coast or Caribbean I can offer up for your time. Let me know. Thanks!

[mrbojangles]

Re: Rough idle when truck is cold

This is a great thread. I'm a proud owner of my first CNG vehicle. I've never replaced coils before: How many are there 4? 6? 8? Do I need to replace the coil pack as well as the coils? Thanks again for all the good info.
Bojangles