Got a problem with the 88 D150 318 TBI that's causing me to pull my hair out. Just started a few weeks ago (probably when the temps started to dip overnight). The truck starts fine, but immediately starts to surge from about 500 rpm to about 1500 rpm over and over. If I give it gas, the engine will smooth out some, but you can still feel the surge. If I let the truck run for about 10 minutes, the surge will eventually go away and the truck runs well. While it's surging, it's pretty much un-driveable. I've checked for vacuum leaks and replaced a couple of older hoses. Pulled the injectors and cleaned them. Replaced the TPS and the Air Intake temp sensor (as it was cracked). Even replaced the EGR valve. I do have a map and an idle control motor on order, but getting tired of throwing parts at the truck. Figured I'd see if anyone else has experienced a similar problem here. The truck is not throwing any error codes. I'm about ready to take it in to a shop, but I'd much rather fix it myself if at all possible.

 

You need to scan it to see what the sensors are reading... But with that being said it sounds like a M.A.P sensor.. How did you set the TPS with out a scan tool??? You would more then likely save yourself alot of money to just bite the bullit and take it somewhere to be fixed...The parts you replaced already cost as much as haveing it dianosed...Bill

 

I reckon you are right. It's just hard to admit defeat sometimes, if you know what I mean. Will see what happens when I put in the MAP when it arrives. If it's still having the same issue, I'll have to take it to a shop and let the professionals take a crack at it. Thanks.

 

Figured I'd update this as I just got the truck back from the shop. Took it in last Saturday and told them about the cold idle surge. Also had noticed that there was a bit of a surge at steady speeds even when the engine was warmed up. They kept it over the weekend to do a cold start on it Monday. Got a call on Monday saying they found a slow O2 sensor and a leaking Fuel Pressure Regulator. They had replaced and I could pick up the truck. Told them I'd pick it up Tuesday morning before work. Bill so far,... $815.
Tuesday morning, I paid the bill and went outside to drive the truck home. As soon as I start it up, there was the surge. (That's why I told them I'd pick it up early in the morning) Went back in, brought the manager out and showed him the problem. He brought it back in the shop and I told him to call me when they had it figured out.
Wednesday they didn't call, so I called them about 2p. They told me they had found a bad fuel injector and so had replaced both of them. They wanted to keep over night and test again Thursday morning. Bill for the injectors,... $440.
Got a call Thursday and they said they had tested and it seemed to be running "like a 1988 truck" now. I told them I'd pick it up this morning (Friday) and told the manager I'd start it up first before I paid.
This morning the truck started up okay and ran fairly good without the surge, but smelled badly of gas while it was warming up. Didn't seem to be a high idle at all. Surge was gone and I was afraid of what they might charge me for next so I paid my bill and drove the truck home. There was no surge at all that I could feel, but the truck seemed to be pretty sluggish. Had to give it a fair amount of pedal to get it up to speed. I'm thinking perhaps they did not get the injectors seated completely and one or both may be leaking into the throttle body. Will seat them tomorrow with the magic rubber mallet and see if that makes a difference. So,... I've paid over $1200 to get rid of this idle surge. Took them almost a week and the truck runs worse when warm now than it did when I brought it in. This is a "well reviewed" shop in the area. They won't get a good review from me.

 

Sounds like you got screwed... O2 sensor is only $150, pressure reg ? $100 and it is still F U. Is it an 88 ???
Make sure they hooked the pressure reg up

 

If you are PC/Laptop savey, You can get one of these to help you DIY.....

 

Yes it is an 88. I checked the injectors and made sure they were seated well. Took the truck out Saturday for a few hours. It's not surging any more. Runs fair but seems to idle rough in gear now, which it didn't do before I took it in. Still some hesitation from a stop when the engine is cold and even when warm, doesn't seem to be very peppy.

I have an OBD II scanner already, but I believe this truck is OBD I. According to the shop, when they got done with the truck it was not throwing any codes. I'll probably pull the plugs next weekend and see how they look. Might try a basic tune up on it and see where that leaves me. If I need to bring it in to a shop, it will be a different one next time.

 

Might need to recheck the timing????
Might do the Wiggle Wiring test... Maybe the shop knocked the connection loose for the SMEC?

 

Typical today ! through a few parts at it and say it's fixed.. Customer pays $$$$

 

I agree... Total B.S.

 

I brought a Nissan truck in for some work years ago and was charged big bucks for a tune up (dual spark plug motor) when the real issue turned out to be a torched head gasket! I made them remove all the tune up items and all related charges. How do these guys live with themselves?

 

Even though it cost me over $1200, I would have been happy (somewhat) if they had got the truck running right. Most of the cost was labor and diagnostics, which they hit me up for 3 times. At least the truck is drivable at this point and I'll just take my time and check everything I can think of that may be causing the poor idle and loss of power. Maybe they did knock something loose somewhere.

 

The auto shop had sent me a link via email to write a review, which I did this afternoon. Didn't pull any punches. Just got a call from the manager of the shop who was very apologetic and told me to bring in the truck and they would get it fixed and wouldn't charge me any more. I guess I'll give them another shot at getting it right. I'm going to drop the truck off Saturday and leave it with them until they are confident it is fixed. I will let you guys know the results sometime next week.

 

Finally got the truck back this Saturday from the shop. Running pretty good now. Slight miss, but they did mention that the compression is a little low on two cylinders. All in all though, it's running pretty good and they even took it in for emissions testing for me and didn't charge for it. Still, a lot to pay to get the truck fixed and it took them three tries and a total of two weeks. Just glad to have it back.

 

Hope it last you awhile now.... Bummer about the 2 low Cylinders.