crisharrison77

I have a 91 LX 5.0. I put a cold air intake on it, after a while, the car would (SOMETIMES) bog at the lower rpm pf each gear, but would pull through it just fine, (mostly happened with first use of the car during the day, or after sitting a while during the day). Since then, I increased the timing to 15, replaced spark plugs. Has had a slow to start issue here and there. 2 days ago, it was doing a slow to start deal, and it smoked the thin black wire to the negative post on the battery. Next turn of the key it cranks right up. I immediately took the battery back to the place I bought it (under warranty). With a brand new battery, car cranks up just fine. Revs up just fine. Put it in gear, try to take off, and it bogs down. then it cleared up. Made it home just fine. I have a 35 minute drive to work. Yesterday morning driving to work, about 20 minutes into the drive, and cruising at about 77mph, the cars just falls off in power (bogs down), and will not exceed 2500 rpm, regardless of what gear I'm in. I find a broken vacuum line, and fix that. Take it for a quick spin, feel nothing wrong. During the drive home, same thing happens as in the morning. Yesterday afternoon, I replace the Ignition coil, and the fuel filter, take the car for a nice HARD 30 minute run, and no issues. this morning coming to work. Same thing happens, 20 minutes into the drive, just bogs down and wont go over 2500 rpm.

Any leads as to what may be causing this issue?

AdderMk2

Does the car still have cats?

crisharrison77

No it does not!

nitrous_bob

i'd hook up a fuel pressure guage that you can see from inside the car ,mount it outside though

when it does it's thing see if fuel pressure is still good (36-40 psi)

you can simply run some braided line off the schrader valve on the rail and zip tie it to the wiper if you wanted to. or just mount it with a guage cup and leave it for good

i'd start there... even though all the electrical issues might indicate spark.... eliminate the easy one and then chase demons after that

crisharrison77

Here's a little more info about the car after having trying to fix it the last couple days, and see what kind of help I can get afrom everyone.

It has a cold air intake.
Items replaced:

Spark Plugs (Gap 45)
Fuel Filter
Ignition Coil
(Test Drive)
Ignition Module (TFI Sensor)
(Test Drive)
Distributor (which of course came with a new PIP Sensor)
(Test Drive)
New plug wires
(Test Drive)

What I have found out during and after the test drives are this. The missing/bucking/bogging does ALSO happen with NO LOAD on the motor ar 2000-2500 rpm. Also the aft spark plug 4 & 8 (ONLY) have un-burnt fuel residue on the threads (But clean tips), of course running very rich, as a co worker of mine said he could smell me before he saw me when driving to work Friday morning (of course this was during the bogging time)

I do not have a code reader yet, and am possibly looking to purchase one tomorrow.

Any suggestions or help would be greatly appreciated.

Thanks

TrimDrip

Things I think it could be is egr sticking open and the maf. I would pull the codes and see what they tell me. The tester is only like 20 bucks and it should have a book to explain all the test your car can preform.

crisharrison77

KOEO Code

96
Fuel Pump secondary circuit failure (Batt to ECA) OR High Speed fuel pump circuit open



KOER

94
Thermactic air system INOP (Left side)

44
Thermactic air system INOP (Right side)

(I do NOT have a smog pump installed and the two hard lines off the back of the block has a hose running one hard line back to the other)

crisharrison77

Also only seems to do it when driving at speeds of 80 or greater when the problem kicks in. The problem then will continue till the car is turned off and just sits for just a minute or two. Then it will drive fine, under 80 mph. I mean I got it back up to 60 for an extended period of time with no issues, even stopping for lights after the long run. But get on the interstate and drive at 80 or more for less than 5 miles and the problem kicks in.

I also replaced the fuel pump relay, and didn't fix it.

TrimDrip

man, I don't really know what to tell you on that. I am trying to remember any car I have ever seen do that and I am drawing a blank.

crisharrison77

Havent been able to do anything trouble shooting wise to the car in the last couple days but thought I'd share this mornings happenings.

So on the drive to work today I figured I'd try something different to maybe help in troubleshooting. My mustang is a manual shift, The last stretch of road before work I decided id push it up over 80 and see if it would do it again, (cause I've driven the car the past couple days but not exceeding 75), and of course it did bog down. WHILE STILL DRIVING ON THE ROAD. I put the car in neutral and shut the car off, and immediately cranked it back up. Just like the initial cranking of any day, at any time, any temp, the car bogged for just a minute and then it was gone (as long as you didn't get over 80 again).

Just food for thought???

I'll update this afternoon, as I ohm out the EEC connector and the EEC itself, along with resetting the timing back to 10 from 15, changing the PCV valve, and checking or cleaning the MAFS.

Thanks for any suggestions or help you wish to give!!!