Low power, smells of fuel, some bucking

[Th3GentleGiant]

I recently picked up my first SHO 2.5 weeks ago. Ever since I've gotten it I've been chasing issues. It's a 91 SHO Plus with 125k on the odometer. It stutters and stuggles on power in all rpms and smells of fuel most of the time. I've been researching all I can before posting and nothing seems to do the trick, so here I am. I've replaced a few parts in the past 2k miles already including:
Fuel filter
Fuel pump
Plugs
Wires
Coolant temp sensor
Tps
Maf
Ignition coil
Dis module
Front cat y pipe assembly

I had the codes pulled at a dealership and was told there aren't any codes (will be getting a code reader myself soon to verify). Everything I've replaced has been OEM spec as the car isn't modded. I do know the car will be needing it's full 60k very soon, but I was hoping to get some regular driving out of it before I really tear into the motor. The PO did an upper 60k a few years back as well. The car struggles in low rpms and after the secondaries open I hear the additional air flow, but the power doesn't come. I smell fuel as if it's running rich, but the plugs don't look as such. No oil in the plug wells as far as I can tell. I'm suspecting possibly a faulty FPR causing rich and lean conditions at different rpms but I don't want to keep tossing parts at the car without results. On first initial cold start it idles rough and low but gets better as it warms up (and power comes with temp a little as well).

I've researched and trouble shooted as much as I can before posting here, but I'm just stumped. Any insight is greatly appreciated. Still very new to the SHO and it's quirks and love it so far, but I'm losing interest as I haven't been able to enjoy the SHO in its full glory yet.

 

[SHOdded]

Welcome, and congrats, I think ...

Where do you smell the fuel from, the exhaust, or the engine bay, or ...? What are the fuel pressures like at the rail, with and without the engine running? Sometimes the regulator fails or the hose leaks. Have you checked the connections to the canister (should be down in front, driverside of engine), maybe the solenoid is not working, and/or the canister is full/overflowing. Banged on the cats/mufflers to see if there's anything rattling (and causing exhaust restriction)?

This might be a useful reference for you:
http://alfitz.com/SHO_Engine_Book.pdf

 

[Th3GentleGiant]

I haven't tracked down where the smell itself is coming from. I believe engine bay as I smell it when driving only with the windows open. I'll let the car idle and try and track the smells origin. Its mostly when in the low rpms when under mild load and I smell it less if not at all in the top end. I did find a vacuum line underneath the IAC with a very brittle T connection that disintegrated once I touched it and replaced that too. Suspected it was for the FPR but I've come to believe otherwise. Think it was for the secondaries?
I'll get a fuel pressure tester on there asap and test the pressure (just need to pick one up). I love how this car has that Schrader valve to test fuel pressure right on top of the motor. I have noticed that the fuel gauge will read roughly 1/8 tank low until I come to a stop. Not sure if that's special to the SHO or not. I'll check the canister once I get in to check the fuel pressure as well. I'm guessing you mean the charcoal canister as well?

The exhaust is completely free of unnatural restriction (actually had hollowed cats but now has new oem cats back in the car). Confirmed this by the exhaust shop that replaced the cats.

I do know it is originally a California car and has been converted to a non Cali ecu as the EGR is there but the collection pipe is removed (PO also included original Cali ecu as well).

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[sperold]

Borrow a scantool before you buy one, as there are a lot of complaints about OBD1 scanners.

Research the paper-clip method on this forum as there are very good articles on the topic. I am with you, I would guess there are some stored codes in there. But the paper-clip method doesn't lie.

If there really are no codes (which seems doubtful), about the only thing that causes problems and generates no code is a dying crank position sensor.
A cam position sensor usually has start-up issues and the tachometer acts strange, and it usually throws a code.

Make sure your new wires follow the routing displayed on this forum, as a lot of repair manuals indicate the routing incorrectly. http://www.shoforum.com/index.php?threads/plug-wire-routing.89091/

You have already done a lot of work on the vehicle and a solution cannot be far away.

 

[Th3GentleGiant]

I'll get in with that paperclip and pull the codes manually. Done by counting the blinking CEL if I remember correctly. Just need to learn the process. Seems pretty self explainatory.

My wires are correct I verified it against multiple different references from the website when I changed out the ignition coil (PO gave me a nice box of spare parts) and then verified again when I put in fresh new wires.

Do I need to reset the ecu after installing any of the parts I've done? Most of these repairs were done while driving the car from East coast to West coast (house was sold and had no choice but to pack and go) so I didn't really get to "reset" things after installing them. I know I need to reset my idle but I don't see how that would effect the rest of the rev range.

Appreciate the input guys. I'll get back asap with any codes and fuel pressure readings. I know I'm close to figuring it out which is why I haven't given up. Just need to spend more time and really learn the car inside and out

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[SHOdded]

I did find a vacuum line underneath the IAC with a very brittle T connection that disintegrated once I touched it and replaced that too. Suspected it was for the FPR but I've come to believe otherwise. Think it was for the secondaries?

Not sure. Possibly EGR related? Can you post a pic? Here are some pics from instructions for an upper 60K
http://web.archive.org/web/20110506202226/http://www.shophoenixproject.com/upper60k/upper60k.htm

I'm guessing you mean the charcoal canister as well?

Correct. If there is a problem in this area, it is usually the solenoid that has gone bad. The usual fix for which is to bypass the solenoid.
http://wikisho.com/wiki/Gasoline_smell_in/around_a_SHO.

Idle reset procedure:
http://wikisho.com/wiki/Idle_Reset_Procedure

 

[sperold]

http://www.shoforum.com/index.php?posts/1328363/ Here is a good explanation of the paper clip method, found in this thread : See post #6 link.

 

[rubydist]

the disintegrating line under the iac is very likely symptomatic of a larger problem with your old vacuum hoses. The next thing I would be doing is to replace vacuum lines, in particular look for the ones that run to the front side of the engine down behind the radiator - those are the purge lines from the fuel tank, and if they are cracked you will get fuel smell endlessly.

I would not worry about idle reset, but I would disconnect the battery overnight so the pcm is completely reset. Then I would drive it a few days and pull codes again. The paperclip method is the best, because obd1 scanners are notoriously unreliable.

The second thing I would do is to pull the top and bottom timing covers off and verify that the cam timing is correct. Don't worry about the lines on the belt, just line up the dots on the cam sprockets with the mark on the metal timing cover, verify that both of them line up, and also that the crank pulley is at 0*. Your lack of power issue could easily be that the cam timing is messed up.

Let us know what you find on those two things.

 

[sperold]

Here is a great site put together by Devin on this forum:

http://www.shopowered.com/

And it has the paper clip method as well as other helpful information in an easy to find location.

 

[DeepPower]

Can anyone tell me if silicone vacuum lines are better than rubber? Do they withstand heat better and last longer?

 

[rubydist]

yes, silicone are better at handling heat and longer life

 

[DeepPower]

I haven't tracked down where the smell itself is coming from. I believe engine bay as I smell it when driving only with the windows open. I'll let the car idle and try and track the smells origin.

Could be one or more of the seals on the injectors needs replacing.

 

[Th3GentleGiant]

Sorry for the long delay guys. Been busy with my move across country. Anyways. Finally got some codes off the car. The KOEO brought these codes:
52- power steering pressure (had new steering rack installed upon purchase of car so possible mishap at that shop)
85- CANP solenoid (charcoal canister?)
Stored codes are
14- ignition pickup erratic (not sure if from previous diagnostics or current issue)
29- VSS (speedo jumps a bit)
67- neutral switch (unsure)

KOER showed
77 - didn't receive "goose" test
52 - power steering

Cylinder balance check came out all clear with 9 blinks.

Going to look into the charcoal canister deal/possibly bypass the solenoid.

Also replaced the FPR and the smell of fuel has dropped 100% but no progress made with how it runs.

As far as how the car runs, on cold starts it idles at ~400rpm or lower but then rises to normal 900-1000 after 30 seconds or so. Until it gets to operating temp it acts as if it has a vac leak (hesistant on throttle blip and sometimes rpms drop a touch). It struggles HARD to get moving especially when cold (sometimes bucks a little bit when cold but never when warmed up). Between 3-4k it feels like things smooth out a touch and some power comes through and feels to fade off once 4k hits. It really feels like its misfiring. I have a cam position sensor ready to go in, but Im hesisitant to do so without the proper alignment tool.


Thanks for the input again and now that Im a bit more settled in my new home Ill be able to be more consistent with testing and getting back to you guys on the results

 

[zoomlater]

Did you get a chance to measure the fuel pressure before changing the FPR? What is the pressure now with key on, but not started. What is the pressure with the engine running.

 

[Th3GentleGiant]

I have not been able to test fuel pressure unfortunately. I have limited resources here and dont know anyone with a fuel pressure tester.

 

[DeepPower]

14- ignition pickup erratic (not sure if from previous diagnostics or current issue)

That looks like the TFI ignition module. Replacing could clear up other codes.

 

[Th3GentleGiant]

That looks like the TFI ignition module. Replacing could clear up other codes.

Where would that be located? Google search hasn't yielded many results for the SHO. Still learning the car as well lol

 

[rubydist]

14 is most likely a crank sensor issue in my experience.

 

[Th3GentleGiant]

Well the car just decided it didnt want to start. Ran to the gas station on lunch break at work and was long enough to get up to temp and now when I go to crank it it just clicks and does nothing. Pretty sure I have the good old water pump and crank sensor issue (especially with that code 14). Have a crank sensor coming in and will hopefully fix it over the weekend

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[Nicklepickle40]

Did you ever solve this issue