Surging Problem - Help

[Lawless]

I have a 1990 Ford Mustang LX with a serious surge problem (off idle). The surge occurs between 1500-2500 rpm and is so bad....you have to clutch in and then accelerate (clutching out) to get it to stop surging. The rich/lean indicator is indicating a lean condition when this is occurring. I bought the car like this and have been trying for the last month to correct this problem. The engine runs fine when accelerating or driving
fast. The car has a 302 with trick flow twisted wedge heads (ported and polished,
o-ringed), Vortech R trim Supercharger (15 pounds of boost at 6000 rpm), GT-40 lower intake, Downs upper, Accufab 70mm throttle body, Pro-m 77mm MAF (calibrated), 36lb injectors, 1 5/8 shorty headers, 3" Mac exhaust, Comp Cam (.597 lift, 230 duration, 114 lobe separation, 1.6 roller rockers, upgraded in tank fuel pump and NOS external fuel pump etc.

After talking to various tech lines I was told a custom programmed chip would solve my problem. I was referred to and ordered a Custom Programmed Chip from Super Chip. It did nothing to correct my problem. I have
diagnosed all the basic systems (to much to mention) and they appear to be fine. I have ordered an adjustable fuel pressure regulator (Aeromotive). The car has a stock regulator, I checked the pressure (with a gauge) it showed 40 at idle and 42 when the engine was revved up. I don't suppose it is the problem but I need one anyway. What should I set it at ? I also ordered new O2 sensors....same story. I am beginning to get frustrated, I am wondering what I should do next ? I thought about replacing the MAF with a different brand. Would that help ? I am going to remove the MAF tonight and clean the wire with electrical cleaner, I was told if oil gets on it (from the K&N), it can goof up.

Oh yeah, I live in Northern Alberta.......... there are no dyno's, speed shops or the like here. I am on my own.

I would appreciate any advice.

Thanks....... Jay

[moponys]

I would have suggested the custom tuned chip too. My basically has the same type of mods and problems as yours and have been told that I need a custom chip to correct the fuel/air ratio. I've heard that JMS chips are the best to get and are only around 300 dollars too. You don't have any type of vacuum leak? Could it be that you cam is rated for really high rpms only?

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TFS twisted wedge heads, TFS street intake, Lunati cam .500/.510 218/226, BBK FPR
BBK shorties, BBK 70mm tb, Pro-m 75mm, ASP pulleys, FMS 3:73, Transgo shiftkit
Flowmasters, Bassani x-pipe, K&N FIPK, FMS 1.6 roller rockers, 9mm wires,24lbs injectors,
190lph fuel pump, MSD cap and rotor, 18" wheels w/street tires

[PKRWUD]

Actually, my first thought while reading your description was a dirty MAF, but who knows. Are there any codes? Try disconnecting the TPS from the harness and hooking up the leads from a DMM (with a bargraph) across the VREF and TP Sig (grn & orange) wires. Set the DMM at ohms, and watch the bar graph as you turn the throttle. There's a good chance that you will find a flat spot, where the bar momentarily stops progressing, or even back steps. I had that happen with my truck, and when I tested it for a smooth voltage increase, it wasn't as evident as it was testing it for resistance. My bar graph jumped significantly in both directions while I slowly rotated my throttle. I replaced the old TPS (only had 60k on it!), and the problem was solved.

Good luck!

Take care
~Chris

------------------
Retired Moderator
MustangNet

My site: JimPorterRacing

RACECAR spelled backwards is RACECAR

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[This message has been edited by PKRWUD (edited 08-09-2001).]

[Lawless]

Originally posted by PKRWUD:
Actually, my first thought while reading your description was a dirty MAF, but who knows. Are there any codes? Try disconnecting the TPS from the harness and hooking up the leads from a DMM (with a bargraph) across the VREF and TP Sig (grn & orange) wires. Set the DMM at ohms, and watch the bar graph as you turn the throttle. There's a good chance that you will find a flat spot, where the bar momentarily stops progressing, or even back steps. I had that happen with my truck, and when I tested it for a smooth voltage increase, it wasn't as evident as it was testing it for resistance. My bar graph jumped significantly in both directions while I slowly rotated my throttle. I replaced the old TPS (only had 60k on it!), and the problem was solved.

Good luck!

Take care
~Chris

I tested the TPS with a ohmmeter and got a clean sweep, I will borrow a digital multi meter and try it again (as you suggested). I inspected the MAF tonight, it says Pro Flow on it. Is that the same as a Pro M ? Is it any good ? I don't have any electrical cleaner so I will clean it tomorrow......... although the two wires look clean.

Thanks for responding...... Jay

[gregs93]

Sounds like a problem I had. My fuel pressure read fine. AFM told me to get a gauge I could read inside the car. when I got that gauge I was able to see that my pressure was dropping when I hit about 2k on the tach. new regulator and that gauge took care of the problem

[Lawless]

I checked for vacuum leaks and found none. I have 10 inches of vacuum at idle.... which appears to be normal for that size of cam.

I have information coming on the cam.

Thanks.......Jay

[Lawless]

Originally posted by gregs93:
Sounds like a problem I had. My fuel pressure read fine. AFM told me to get a gauge I could read inside the car. when I got that gauge I was able to see that my pressure was dropping when I hit about 2k on the tach. new regulator and that gauge took care of the problem

I performed the same check and it held a steady 42 while driving..... I guess I should have mentioned that..... Thanks anyway.... Jay

[moosejaw]

This a challenging problem.
I have some questions 1st. Do you have a blower bypass valve and is its connections to blower inlet anywhere near the air meter.

This kinda sounds like the bypass valve cycling open and shut at low load causing flow disruptions. If vortech shipped the Bosch bypass with your kit this could be the culprit. Adjustable bypasses are easier to setup for different cams.

To test this pull the vacuum line from the bypass and plug it. Drive the car with low to part throttle (no boost) and see what happens. It will idle funny with the bypass undone because the blower will push more air past the throttle blade. Look for that lean out condition while driving and don't rev it high with out the bypass!! The blower belt could jump off when you shut the throttle.

Hey PKRWUD lets see if we can get this one solved quickly.

Mike



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Live near St.Louis?
Check out Mustang Muscle and Dyno in High Ridge, MO
Check out my ride.

[PKRWUD]

You're right, this is a tough one. Especially without being there to experience it in person! You may be on to something. I really don't know, but what you've suggested makes alot of sense. I still want to know what the ECM has to say!

How about some codes!

Take care
~Chris

[Lawless]

Originally posted by moosejaw:
This a challenging problem.
I have some questions 1st. Do you have a blower bypass valve and is its connections to blower inlet anywhere near the air meter.

This kinda sounds like the bypass valve cycling open and shut at low load causing flow disruptions. If vortech shipped the Bosch bypass with your kit this could be the culprit. Adjustable bypasses are easier to setup for different cams.

To test this pull the vacuum line from the bypass and plug it. Drive the car with low to part throttle (no boost) and see what happens. It will idle funny with the bypass undone because the blower will push more air past the throttle blade. Look for that lean out condition while driving and don't rev it high with out the bypass!! The blower belt could jump off when you shut the throttle.

Hey PKRWUD lets see if we can get this one solved quickly.

Mike

Mike and Chris,

The MAF is located inside the passenger fender, it is mounted to a homemade power tube (not bad quality) from the back of the Vortech.

The racing bypass (HKS) is located in the tube that connects the Vortech to the throttle body. The top vacuum port is connected to manifold vacuum. The bottom port isn't connected to anything, also on the bottom is a adjustment bolt. I called HKS and they said the bottom port and adjuster bolt to limit your boost. I left it alone. The factory wiring harness was lengthened poorly (to relocate the maf to the fender) so I rewired it with the correct guage and properly soldered it up. I unbolted the sensor and cleaned the two wires.

I reinstalled it and tested it. No difference. The sensor is engraved to show it is recalibrated for the 36lb injectors.

I replaced both 02 sensors with Bosch, no difference. I received my new pressure regulator but havent had time to install it. I don't think that is the problem. The factory one is pushing 42 psi.

I will unplug the bypass valve (like you suggested) although I think I tried that already.

I hooked up a Snap On scanner, there were no codes. No trouble lights come on the dash ever.

The blower is run by a cog belt system.

The rich lean indicator does not register at idle, when you rpm it, the colors are all good. When the car surges..... most of the time the indicator is not registering.

Questions: Have you guys heard of Pro-Flo ?, (that is the brand of the maf). I am concerned about that.

Could the cam be to radical ? That's what the previous owner said. I am not sure on that one.

Any other suggestions ?

Thanks for your time.

Jay

[Lawless]

Mike and Chris,

One more question: The air cleaner (round K&N )is mounted directly to the maf (which is located in the fender). It is pointing down at a angle. Would that type of set up effect the way the maf sensor reads ? (i.e. turbulance etc.). I was thinking of mounting the maf directly to the throttle body (bypassing the blower) for a test.

Thanks

Jay

[PKRWUD]

I'll let you know right now that blowers are not my strong point, and that Mike will probably be of more help than I will, but your last comment made me think. Did you clean your MAF? The only problem I am aware of with having a K&N mounted the way you do is that the probablity of oil getting from the filter to the MAF is pretty high, and an oily MAF wire will affect driveability. I am not familiar with your brand of MAF, though.

I am surprised that the car could experience such a severe drivability problem without the ECM noting anything. have you tried driving with the scanner hook up and monitored your system? I would like to know if the ECM concurs with your rich/lean indicator when this happens. The idea of bypassing the blower will tell you if it's blower related, so to "cut the pie in half", you might want to try that. It's solvable. Difficult, but solvable!

Take care
~Chris

------------------
Retired Moderator
MustangNet

My site: JimPorterRacing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

[moosejaw]

Lets see...

Addressing the lean condition at idle. Do you have a low temp thermostat? Is the motor getting completely warmed up?

Do you have hard starts with the 36# injectors?

Ok, the HKS is big which is good. I believe it is similar in size and adjustability to the Vortech race unit. You didn't say specifically if the bypass routed back the blower inlet. It is important that the air isn't dumped out.

You can adjust the bypass to be more compatible with your cruising rpm and vacuum. Loosen the locknut and turn the adjust screw in. This will change the opening point of the valve to be "more vacuum". Lets say it is set at 4" HG. You can adjust it in to say 8" HG. Now the valve will close more quickly when loading. Since your idle vacuum is about 10" HG this could be a help. The best way to set the valve is with a hand vacuum pump. There is a limit to how far you can adjust these valves. Verify the stroke on the valve when complete, it should stroke the same distance before and after adjusting. Adjusting to far will jam the diaphragm and keep the valve from fully opening.


Operational Note: The bypass needs to open when at high rpm with the throttle closed or part closed. This is where the blower makes a ton of air flow and pressure. With out a means to relieve this airflow the blower will "overload" and possibly kick the belt off or damage the drive gears, with your cogged setup. Ever notice how much vacuum the motor pulls when decelerating from rpm? It will pull 20-25" HG sometimes. This is when the bypass earns it money. Lots of rpm with a shut throttle is when blower belts get destroyed.

The point here is the setpoint change from 4" to say even 11" is not a big deal (as long as the valve does open) because the conditions stated above are when the bypass is really needed. I had an early Vortech s trim on my 92 f250 and they didn't even give me a bypass with that kit! Truth is it never threw a belt but you could feel the surge sometimes after racing it.

Mike




------------------
Live near St.Louis?
Check out Mustang Muscle and Dyno in High Ridge, MO
Check out my ride.

[PKRWUD]

Yeah, What he said.

Take care
~Chris

------------------
Retired Moderator
MustangNet

My site: JimPorterRacing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

[Lawless]

Mike and Chris.......

I cleaned the MAF, no difference. I had a tech hook up a Snap On Scanner to the ECM (2 weeks ago). The tech said the Snap On scanner would basically only read codes (which it didn't have). I have got the number of a Ford Tech who has access to a Ford Scanner, I will call him today so maybe we can hook it up and test drive the car..... maybe see whats going on. I have not bypassed the blower yet, it's on my list. I don't know what the thermostat is, but the car runs between 180 and 200. The car starts fine with the 36 lb injectors. Why does the racing bypass have to be routed back to the inlet of the blower blower. Mine isn't and I just made that impossible. I noticed the body of the bypass was rubbing on the inner fender, I reversed the bypass so the outlet was facing towards the inner fender, but then the outlet was rubbing...... so I shortened it removing the about 1/2 inch (no more nipple). Whoops !

Some progress (and anti progress) yesterday, I installed the adjustable fuel regulator and set it according to instructions, 48 psi static (vacuum line disconnected). It runs about 44 psi with the vacuum line connected at idle. The surge was cut in about half, car idles smoother, less exhaust noise and the lean rich indicator is toggling in between lean and medium (green)at idle (thats new). I am going to feed it some more pressure (in 2 psi increments) today and see what happens. Now for the bad news, I felt confident enough to start rpming the car hard yesterday...... I hit a surge at about 5,000 rpm, feels like hitting a rev limiter or maybe a miss. Hmmmmm..... and I thought I was getting somewhere. :0(
Anyway I will try that again with the fuel pressure guage hooked up.......

Later

Jay

[95mustanggt]

Originally posted by Lawless:
Oh yeah, I live in Northern Alberta.......... there are no dyno's, speed shops or the like here. I am on my own.

Jay,

Your problem is that you live in Fort Mac.


(j/k I'm originally from Edmonton. Sorry I just had to add that.)

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1995 Mustang GT

[andy669]

Well Jay, to answer youre one question, you do have a pro-m maf. (like you originally thought) And yes, the 77's are excellent meters. As everyone here is going to tell you, the change in fuel pressure is only going to last so long. Before too long the computer is going to adapt. It sounds to me like you are having fuel problems. If thats the case, getting some type of fuel management system would give you good driveability along with performance. You mentioned that you had already tried a superchip. Well, a chip is only as good as the tuner who burned it. Call JMS, they know what they are doing. Or go all out and get a PMS or EPEC or something like that.
good luck
andy

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3 Black 94 GT Vert. AODE/TKO conversion, 3:73's, ported X-305's, GT40 manifolds, 75mm TB, 30lbers, PMS, 300 horse Top Gun wet kit, and all the other little stuff

[Lawless]

Mike, Chris, Andy & others......

I brought the fuel pressure up to 58 psi static with no noticeable improvement. I returned it back to 48 psi.

I connected a vacuum pump to the top port of the HKS Bypass Valve (the one manifold vacuum was connected to, the one HKS told me to connect it to)........ wouldn't hold vacuum (vacuum leak), the valve never moved. I then hooked the pump to the bottom port and at 13 HG the valve began to open. I tried the adjustment bolt and all that did was control the speed of the release (once there was less then 13 HG). All the way out meant the valve closed faster, in slower. Something must be wrong here, sounds like I need new valve. The oulet faced the wrong way anyway and well the missing nipple thing. What should I buy ? It also sounds like I need a power pipe with inlet for the bypass valve. What kind should I buy ?. I'd like to keep the MAP in the fender. Could this have anything to do with my "low speed surge", it does not sound like it would effect the high speed one ? Basically the way it was operating..... the valve was closed all the time and I had a minor vacuum leak.

I'll call JMS and ask them some questions. Does anyone know their number ? Do they have a toll free one ? I need to eat this week........lol

Jay

[Lawless]

Originally posted by 95mustanggt:
Jay,

Your problem is that you live in Fort Mac.


(j/k I'm originally from Edmonton. Sorry I just had to add that.)

Rub it in !

[Lawless]

Originally posted by 95mustanggt:
Jay,

Your problem is that you live in Fort Mac.


(j/k I'm originally from Edmonton. Sorry I just had to add that.)

Rub it in !