Engine Bogging down

J

Jarhead

New member
I have a 99 Lightning. 72,000 miles. It was running fine one day, the next day after waiting for a light when I hit the accelertor it totally bogged down when I was turning. I ran a dianostic on it and received P0171 and P0174 system too lean errors. Based on information that I found, I replaced the fuel filter, no change. I talked to the shop manager at Ford, he said I had a bad EGR valve, based on my description of my problem. I went ahead and replaced this as well. It helped a little, but she still won't accelerate properly and still intermitently bogs down when I accelerate. If I let up on the accelerator its ok. I've cleaned my cold air intake. The mass air flow sensor seems to be working fine. I wasn't able to locate any vacuum leaks by spraying brake cleaner on her. ????? Any help would be greatly appreciated!
 
You need to check your fuel pressure, also if you have a scanner post maf readings. Lean condition could be 02's or vacuum leak, however it would not bog like this on accel. My guess is a fuel pressure issue or your maf counts are all over the place.
 
Thanks Sonic- My MAF is currently reading at .16.

So your thinking 02 sensors-that seems to be a re-occuring issue with alot of the Lightnings from what I've read on the board. Sounds like alot of problems are also with this "90 elbow hose" going to the back of the intake. I was thinking that might be my next step, unless its the 02 sensors.
 
Does maf reading bounce around?

Check with your scanner o2 readings, you may have a lazy one or a vacuum leak up near intake.
 
I just checked the MAF reading again after having it idling for a bit. I had readings from 1.56 - .91 ????

I don't know what the 02 is reading. How do I go about checking that?
 
we need a baro reading. it will be in hz. if you are near sea level it should read near 157hz. the more above sea level the lower it will be. the baro reading is a learned value infered by the maf. an egr valve will not cause a lean condition.
 
I'm in Tampa Fl. The barometer locally right now is 29.95in. I couldn't find how to a convert it into hz.

Would a MAF be throwing a too lean error? (p0171 p0174) I look into the MAF. Is this something I should only use a Ford part on, or am I alright using something else?

Any suggestions...

Thanks Matt
 
Hey Sonic you said you thought it might be a fuel issue. If thats it, what do you do? I thought I read that theres a safety feature that prevents you from syphoning it. Do you just run it, and then replace the fuel filter again? I thought thats what it was initially right when this started.
 
Jarhead said:
I'm in Tampa Fl. The barometer locally right now is 29.95in. I couldn't find how to a convert it into hz.

Would a MAF be throwing a too lean error? (p0171 p0174) I look into the MAF. Is this something I should only use a Ford part on, or am I alright using something else?

Any suggestions...

Thanks Matt
Click to expand...

use the ford part only.....!!!! yes a bad maf can cause those codes. seen it countless times. especially if the baro is not right. baro is calculated from maf readings. when i mention baro i dont mean your local weather barometer reading....baro is a value that can be viewed with a scantool. we need that value.
 
clean the maf sensor leads with some CRC MAF CLeaner before you go spending money on a new maf.
 
I would hook up a manual fuel pressure gauge and see if there is a drop in fuel pressure then I would check the pump or the fuel filter to see if it is clogged. If fuel pressure checks out my I would bank on having a maf issue, try cleaning it but if you can borrow one to see if that is the cause. If you are not running a different tune ie to run a sct2400 maf, you can run a stock one. I can ship you one for 10% over dealer cost.
 
thePUNISHER said:
use the ford part only.....!!!! yes a bad maf can cause those codes. seen it countless times. especially if the baro is not right. baro is calculated from maf readings. when i mention baro i dont mean your local weather barometer reading....baro is a value that can be viewed with a scantool. we need that value.
Click to expand...

Thanks BigPun I check for the baro on the scanner that I have tonight. I don't remember seeing any readings in hz on her. I had a feeling you were wanting something other than the weather. I'm a bit of a novice when it comes to auto repair,but I'm tired of getting screwed over.
 
Yeah BGSTEW (Semper Fi) - I think I'll give that MAF a cleaning tonight, then I'll follow Sonic's suggestion with checking the fuel pressure. I have already replaced the fuel filter on her. If its bad gas though, is it safe to just burn it off?
 
Ok, cleaned the MAF with the spray, no change. I'm trying to decide which to do next: Replace the MAF, or replace the O2 sensor. Any suggestions. This thing will not go faster than 35-40 tops right now before bogging. If neither the MAF or the O2 sensor works, I'll burn off the tank of gas. Problem is shes almost filled up and she really isn't drivable right now. Then I'll take her to the"professionals" up at Ford and get screwed.
 
02 would not make it bog, it would just set a code. Can you take a manual fuel pressure reading at bog point, before you start just changing parts.
 
I was up at the Ford, the parts dept guy (who use to own a Lightning) says they don't carry the MAF and I should go after market to replace it. So I go to auto zone and I'm talking to the guy cause I wanted to see about trying a different MAF to see if its bad or not. Anyways the guy at AZ shows me this laminated sheet talking about the p0171 and p0174 too lean codes. It said the majority of the time its a bad MAF. I wanted to just buy a new MAF and try it and then bring it back if it didn't work. But because its an electrical component they won't take a return. They don't have the Bosch one in stock at the store closest to me, so I didn't bother driving to get the other one/ and you all were saying I should only use Ford stuff. But I'm thinking that since I'm gonna have to buy one that maybe I'd go after market. Anyways, I was checking out the Big Air MAF or the Sniper Bazooka 95mm, anybody have any experience with either of these. Or have any recommendations?

I'm still working on checking the fuel pressure reading. But like I said I'm a novice so I'm buying stuff as I go.
 
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