When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So I got my top end all put together after taking it apart and cleaning. I put in new injectors from Jon at FIC because I’d been having a stutter/hesitation at 2500+ RPMs or on a steep hill climb. The injectors didn’t help.
The problem only only shows up under extreme conditions-on flat ground, as long as I don’t floor it, I can easily reach 70mph with no issue. Flooring it, or driving up a steep incline are the only two times it shows up. Even so, it is an erratic stutter.
I doubt its spark-I don’t think spark would only show up in those conditions and no other time.
Injectors are about 3 months old pulled from my wrecked 1985, no problems from them in that car.
Clutch feels a little soft-I don’t know what a slipping clutch feels like but I’m not ruling that out as possible.
I need to go check the TPS setting and I might swap the IAC, but it idles perfectly so I’m doubting those are the source of the issue.
So I got my top end all put together after taking it apart and cleaning. I put in new injectors from Jon at FIC because I’d been having a stutter/hesitation at 2500+ RPMs or on a steep hill climb. The injectors didn’t help.
The problem only only shows up under extreme conditions-on flat ground, as long as I don’t floor it, I can easily reach 70mph with no issue. Flooring it, or driving up a steep incline are the only two times it shows up. Even so, it is an erratic stutter.
I doubt its spark-I don’t think spark would only show up in those conditions and no other time.
Injectors are about 3 months old pulled from my wrecked 1985, no problems from them in that car.
Clutch feels a little soft-I don’t know what a slipping clutch feels like but I’m not ruling that out as possible.
I need to go check the TPS setting and I might swap the IAC, but it idles perfectly so I’m doubting those are the source of the issue.
Any other thoughts? Or things I should consider?
The conditions you describe are often associated with ignition problems. Did it do this before you took it apart?
I took it out for another drive this evening, because I just got it back up and running and couldn't stay away
The hesitation is still there, but it's less pronounced. I couldn't get it to do it under acceleration at all, and it only did it once on the steepest hill (the one I live on) around-it's seriously a 15 % grade so definitely a lot of load there.
Only thing different from earlier is adding some Sea Foam to the tank. Could also be coincidental, or a gremlin working its way out of the system? Just thought I'd add that info. It's only a single data point so I'm hesitant to say it's better overall.
Can you be specific on how I should check this? From what you said it sounds like I should take the cap off and try to wiggle the rotor?
Yes, you need to take the distributor cap off (and probably rotor too). Look at the tip of the rotor and the contact points in the cap to see if there is any wear or signs of the two rubbing. This will only show up if the bushings are severely worn. Then wiggle the shaft back and forth looking and feeling for side play. Try different angles too. Sometimes a stutter like you describe will be due to worn bushings - under load the shaft wobbles and can cause misfires from changing gaps between the mag pickup and reluctor wheel or the rotor and cap points. Basically there should be no movement at all if the bushings are ok.
Yes, you need to take the distributor cap off (and probably rotor too). Look at the tip of the rotor and the contact points in the cap to see if there is any wear or signs of the two rubbing. This will only show up if the bushings are severely worn. Then wiggle the shaft back and forth looking and feeling for side play. Try different angles too. Sometimes a stutter like you describe will be due to worn bushings - under load the shaft wobbles and can cause misfires from changing gaps between the mag pickup and reluctor wheel or the rotor and cap points. Basically there should be no movement at all if the bushings are ok.
Some more information-I tried to rev the engine after I first started her up last night (yes, I was showing off). Instead of revving, it just about died, and THEN revved. It definitely took a second to rev for me. Maybe a vacuum leak, although I literally just took everything apart and put it back together and checked it all-I don't think it's a vac leak. I've seen it mentioned that it's the TPS being off-I'd believe that.
On my last car, I stripped the TPS wires a little bit so I could put alligator clips on to check voltage. Is there a better way to check TPS voltage? I don't want to destroy the wires if I can help it.
Some more information-I tried to rev the engine after I first started her up last night (yes, I was showing off). Instead of revving, it just about died, and THEN revved. It definitely took a second to rev for me. Maybe a vacuum leak, although I literally just took everything apart and put it back together and checked it all-I don't think it's a vac leak. I've seen it mentioned that it's the TPS being off-I'd believe that.
On my last car, I stripped the TPS wires a little bit so I could put alligator clips on to check voltage. Is there a better way to check TPS voltage? I don't want to destroy the wires if I can help it.
Yes, Mid America Motorworks has this very tool. It works great. Here is a link to it.
ooo, cool...I didn't even think that there would be such a tool in existence...
Thanks for the link!
EDIT: I have the wiring harness from my old car. I'm wondering if it would be worth it to cut that up and make these sorts of tools for myself. Wouldn't be hard to do if I'm willing to ruin the old harness (which, btw, is already NOT in great shape and missing connectors and such. So I couldn't sell it as a good condition one). Since the old car is a parts car, I might be ok with it. I'm kinda on a budget these days so if I can do something for free I might want to do that.
Would love advice on whether that's a really bad idea or not.
Last edited by Bfenty; 10-27-2017 at 11:41 AM.
Reason: More info
last night I did a test drive with a mechanically inclined friend who helps me with projects sometimes. We were able to get the misfire to repeat if we kept it right at 1k RPMs on a hill-it was a consistent misfire then. It also kicked in when really flooring it-2500-3000 RPMs, but at that point it wasn't consistent.
After talking about it, we agree it is probably spark-related (I know that's been mentioned in this thread previously). I'll try to check the TPS today, as well as pull apart the distributor to have a look, as well as swap plugs/wires.
Im not convinced its an ignition issue just yet. Id like to know the fuel pressure at all conditions including the problem condition. Hows the fuel filter and pump assembly? Did you pull the sending unit and look at it? Make sure the small hose from the pick up tube to the pump isnt split. Does this issue happen when the tank is full or 1/2 or no difference? Still lots of testing needing to be done imo.
rule out fuel pressure by putting the pressure gauge taped to the windshield and driving around re-creating the hesitation. I highly doubt it but at least that will give you peace of mind on fuel. The needle should drop during hesitation. If it's fuel.
I have this exact situation on my 86. I found a spark plug wire grounding it self to the engine. took the wire off and found this.
big surprise this wire was arcing to the l98's air injection tail.
spark issues that are intermittent tend to show up as trailer jerking or fish biting. In my previous 87 my distributor cap was falling apart inside and created the exact same feeling. it's all about the spark not making it to the cylinder. So you get a temporary reduction in power which causes the jerking and hesitating and fish biting sensation.
Adjusted the TPS. It was at 0.4 volts at idle, and maxed out around 3 volts. I replaced it with a nearly new one and adjusted correctly. She ran a little better but still had the fish biting issue around 2500-3000 RPM and while hill climbing.
Pulled spark plugs, didn’t take a photo but they appear to be running lean, not rich. I still need to check fuel pressure, just have to get the gauge. I’m starting to suspect a low fuel pressure issue although I could be mistaken. Just a hunch I guess.
The TPS should be .525 DCV according to the shop manual. Make sure you keep the volt meter going while torquing down the bolts because mine jumped from .525 to .610 during the torquing. I just went through the same thing and after replacing the TPS and verifying the voltage, my hesitation went away. Most "manuals" tell you to mark the position but that is not the best way. You have to tap into the wiring harness and verify the voltage between the ground and the signal wire.
I’ll double check the TPS but on my other car it was .54 volts and no issue...
im a little hesitant to mess with timing, trying to get everything bone stock working before I experiment. Was your hesitation at high load only? My gut still tells me it’s fuel, I really need to test that more thoroughly. Babies make car work difficult, at least until they’re older and can help...
I’ll double check the TPS but on my other car it was .54 volts and no issue...
im a little hesitant to mess with timing, trying to get everything bone stock working before I experiment. Was your hesitation at high load only? My gut still tells me it’s fuel, I really need to test that more thoroughly. Babies make car work difficult, at least until they’re older and can help...
Get the .54 set but check the timing and also check the Harmonic balacer did not spin because of age , then experiment with 9-11 btdc timing
Here is a pic of my old balancer it was off 1/4 of an inch
10-22-2017, 06:36 PM
1985 4+3 hesitation under load
