Wild 90

Im not very active on this forum, but im to a point where i need help. Little history on the car, 1987 IROC. TPI 350/700r4/9 bolt rear.Healthy built engine and trans (was in the car when i bought it, not a clue of the specs). It has a BBK power plus throttle body and long tube headers on it. The car was storm damaged in a tornado in 2011. It has 1000 minor problems but im just trying to get it to run right for the moment. The Tach is not right, the fuel gauge does not work, heater core is bypassed (leaking), radio does not work, and the electric fans run constantly (even tho they seem to be wired correctly to the computer???) I do, however, have a snap on OBD1 scan tool. The car runs pretty good as long as you are easy on it, but sometimes it sets a code 33 for the MAF sensor. The car is very strong until at very high rpm (roughly 1000 or so rpm before the shift). After it shifts, it is strong again until the rpm climbs into that range again. (im assuming 4500-5500 or so, like i said, tach don't work correctly). When it is in that range, it seems to miss and pop out the exhaust. It sounds like a over-revved points style ignition system (when the ignition starts breaking down) Im not ruling out lean fuel, although the fuel pump is new and pressure is to spec. Im needing to know what to look on the scan tool as a tell-tale sign of the problem. My MAF readings seem to smoothly increase from about 8-11 or so at idle to very near 200 at WOT. Im not sure why it is setting code 33. Tps is also very smooth and to spec. Im not against putting a MAF sensor on the car, so long as i can tell that thats whats wrong with it. It also has intermittent high idle issues (not crazy high, but the scanner shows the computer is commanding it to idle 600 rpm, and it gets into the 1200 range at idle at times. Other times it idles 600 rpm. Dirty injectors are another concern i have, the car sat from 2011 until i bought it a couple of months ago. I have run tons of sea foam thru it to no avail. It has a new cap, rotor, wires and plugs in it. Im not sure where to go next in diagnosing the problem. Any input would be greatly appreciated.

Tuned Performance

iTrader: (92)

Has the maf high code been a ongoing issue ?

Wild 90

Yes. It has done it since i have had the car running. Sometimes it will go days without setting it, other times it will set it a mile from the house. Like i said, i have a scan tool and can see MAF readings but don't really know what they are supposed to be.

Tuned Performance

iTrader: (92)

https://www.thirdgen.org/forums/tpi/...ions-here.html

Chad85T/A

iTrader: (1)

My TPI was having a similar issue to what you are describing. It may not be the same thing, but worth a look. My crank case breather hose had a small crack in it that leaked a minute amount of air and at WOT just about 45-4800 RPM's it would cut out and pop. This is the hose on the pass side that runs from the throttle body to the valve cover. On a MAF system every bit of air has to run through the MAF, including the PCV vacuum. I just stumbled upon this by chance and replaced the hose. It fixed the problem and I didn't even realize what I did until my next WOT pull. It actually took me by surprise when the car didn't pop , so I put 2&2 together and decided it had to have been that hose. Sure enough when I inspected it I found a small crack.

Wild 90

Speak of the freaking devil, my car does not have that grommet in the passenger valve cover. If thats all thats wrong with it, i will owe you a million. I have looked for that grommet and cannot locate one at the parts store. Would you have any way to get me a part number to cross reference or order one online?? That would explain the high idle issues too, I don't have anything hooked up to vacuum other than the FPR and the brake booster, so im fairly sure its not leaking vacuum.

Bob88GTA

iTrader: (2)

Advance Auto
Wells Part No. PCG100
$4.49

Wild 90

Thats not the one my car has. The PCV valve in the drivers valve cover is in a gromet like that, but the one on the passenger is different. It makes a 90° bend and the plastic tube slides into it. I could fabricate something to work, just have not put the time into it.

Wild 90

You can see the grommet i need here at point A. Its one piece on my car.

Bob88GTA

iTrader: (2)

They have grommets and elbows in the HELP section at Advance and Auto Zone, I know, I bought that same grommet and elbow you're pointing too. "A"

Wild 90

I looked for one a while back, but oreillys didn have one and i just pretty much gave up and said "i'll fix that one day" Never really thought about the PCV pulling unmetered air into the intake. I will look for one again today and see what i can come up with. I'll build one if i can't find it.

Bob88GTA

iTrader: (2)

Is there a salvage yard near you? The grommets get pretty hard.

Wild 90

Not with any of these cars in it. When scrap prices spiked around here a couple of years ago, both of my main salvage yards crushed everything on the lot and closed. Only 1 decent one within about 100 miles of here and its mostly trucks. I'll gut a old pcv valve and make it work if i can't come up with something else.

Chad85T/A

iTrader: (1)

Mine has aftermarket valve covers. I got a rubber block off and cut the bottom out of it and used a universal 90 that fit tight, and then a length of brake booster hose.

Chad85T/A

iTrader: (1)

Btw, if that fixes it I'll be checking the mailbox for that million 😉

Wild 90

Well, it did not fix it. It did help its responsiveness, but at higher rpm, im still getting the lack of power and popping out the exhaust. I have noticed that the headlights flicker at times when it has done it in the past, but last night the headlights were flickering really bad when it did it, it had enough of a voltage drop to reset the radio. Anyone seen anything of the sort?

Bob88GTA

iTrader: (2)

Well, did you check the easy things as in Battery Terminals and associated connections? Also check your ICM and the pickup coil in the distributor. Cutting out like that is like turning your ignition on and off. IDK, give it a look.

Wild 90

Iv been over it several times. Car got a new battery 3 days ago. Could the electric fans be cycling on-off-on-off and causing issues? I know they pull a lot of current on startup.

Bob88GTA

iTrader: (2)

Not enough to do what you're mentioning unless the fan motors are severely bad and shorting out within themselves.
What is your Alternator putting out? As in volts?

Wild 90

It shows 14.6 with a DMM at idle. volt gauge stands straight up past 18v with it running but its not right. Are these cars rev limited?

Bob88GTA

iTrader: (2)

Not enough to do what you're mentioning unless the fan motors are severely bad and shorting out within themselves.
What is your Alternator putting out? As in volts?

It really sounds like an Ignition issue. Have your ICM and pick up coil checked, also the main coil.

Wild 90

How would this cause the current drop? It has never done it like it did last night before. Iv noticed the lights flicker before but now its bad, Like nearly going off and on. It only does it when the engine is acting up (when you are in that rpm range). It also set the code 33 again last night.

Chad85T/A

iTrader: (1)

😕 I was really hoping to retire off that. The power cutting out like that just about had to be a connection issue. Have you checked your grounds? Especially the main one?

Wild 90

Yes, i have checked all the grounds, they are all clean and present (main at engine block, passenger fender ground, and strap behind passenger head) I think i may be having an alternator issue. I know voltage can do some crazy stuff on a fuel injected motor. I know the FAN fuse has to be hot for the alternator to charge. Wonder if the computer may be cutting power to that fuse under WOT? There is no telling if the car is wired up properly. I know there are certain things it does cut. I'll wire up a test light inline and see if its having power cut. If its not, Its gotta be the alternator acting up. I cleaned the connections at the starter, alternator,and all the grounds. It did seem to somewhat help, its not bad enough to make the radio cut off anymore but it still is dimming the headlights considerably. The volt gauge dances up and down and the lights look like they are being changed from high to low back and fourth when they are just left on low. What are the chances im having a high rpm alternator failure?? Alternator was new in 2011 probably had 5 miles on it before i got the car, but it sat from then till now.

Chad85T/A

iTrader: (1)

Is you belt tight enough to not slip at high RPM? Is seems like the battery would have enough power to keep everything on while the alt is doing this. I can see it dimming the lights if the alt is fluctuating, but not completely cutting power.

Wild 90

Yes, belt is new and tight. Im going to wire a test light inline with my energize wire on my alt and see if i can tell whats going on. I know these cars will not run worth a crap if the alt is not charging. Already fought that battle with it with an incorrect volt gauge and a rat chewed wire going to the alt. I may still have issues with the energize wire. May be this weekend before i have time to do anything with it, the DD is down with exhaust issues (pipe broke off the manifold on my s10) so i gotta get that fixed first so i can quit driving the 3/4 ton to work.

Wild 90

I found out last night that i can make the car have the voltage issue in neutral if its revved fairly high. It seems to be getting worse again. I plan on unplugging the alt and hooking my jumper cables between it and my running truck and seeing what happens.

May just be a bad alternator.

Wild 90

It seems that the alternator on the car is acting up, but thats not whats making it run funky. That being said, i believe i have figured out that there is nothing wrong with the running of the car at all. I never thought about compression ratio on this thing, If you run premium gas in it, the problem goes away. Im assuming the knock sensor is pulling the time back on it exactly like it is supposed to if you run too low octane fuel in it. I am still setting a MAF code from time to time, got a new pigtail ordered for it. If that does not fix it, yall may see a thread about checking a MAF sensor soon. Thanks to all that replied, especially about the PCV hose, I'd probably have fought that unknowingly for months until i happened to fix it. Anyway, thanks again for the help.